I had a lot of fun with this, and decided to share. No no other mods or downloads needed.
Right now there is no restriction on who you can make a companion and I haven't tested every NPC.
-If that character is part of an ongoing or upcoming quest, for example, there may be untoward effects.

NOTE: Uncommonly, something may happen, the cause of which I was never able to determine, that
-will cause companions to not respond. A fix for this is to restore a previous save.
*** SAVE A NEW GAME OFTEN *** so you can go back if everything gets fubar.
I'd like to apologize if it seems unfinished, I've moved on to other things and may revisit modding at some point.
That being said, anyone may use portions of this mod to create other mods as long as credit is given to the author.


Name: Groovy Companions - Make Anyone a Companion
Author: Drayk Cannon
Version: 1.0
Date: 8/25/2020
Category: Companions
Source: https://www.nexusmods.com/newvegas/mods/69763

===============
Description:
===============

In addition to the above:
You can set a hangout spot for each of your companions, or have them guard their current location.
When you fire a companion, you have the option of sending them to the Lucky 38 Casino.
---As long as you've discovered it.
Message box menu rather than dialogue menu driven. / The regular companion wheel will not work.
Realism mode can be toggled in the Setup Menu.
---Realism mode means you will pay them a small fee every day for them to accompany you.
NVSE users get extras, including the ability to give your companions an attack order.
Version 1.0: I can't test every scenario, but I have a solid grasp on things. That being said:
---Create a new save often
---Understand that accidentally shooting or striking your companion may cause you to gain infamy
----with their faction. I'm still trying to figure out how to counteract this.

===============
Details:
===============

Setup menu will activate when the mod is first loaded, and initial character setup is complete.

Initial Setup:
==============
Settings can be changed at any time by using [Groovy Companions Setup] in your Pip-Boy.
This is located in the "Aid" section.
1. You will be asked if you are using NVSE (New Vegas Script Extender) - select Yes or No.
2. If Yes is selected, you will need to bind a key to be used for the Companion Menu.
---Follow the instructions to bind the key.

Activating the Setup Menu:
==========================
Left-Click on [Groovy Companion Setup] in the Aid section of your Pip-Boy.
Current settings, companion count, and other information is displayed.
Menu Options:
1. "I'm ready to pick a companion." (Non-NVSE Only)
---When this is selected, an extra option appears when you activate an NPC, allowing you to
----choose them as a companion. You cannot talk to NPCs while this is on!
2. "I don't want to choose a companion now." (Non-NVSE Only)
---Removes the extra option when activating an NPC.
3. "Create a clone companion." (Clone yourself and make them your companion)
---Limit of 1 clone companion due to things I'd rather not mention.
4. "Change NVSE usage." (Enable or disable NVSE extras)
5. "Change NVSE keybinding." (NVSE Only)
6. "Toggle auto-add missing items."
---(If ON, periodically checks to see if needed items are in your inventory, and adds them if they
----are not. Turn this OFF if you have a mod enabled that removes items from your inventory, or
----are going in a quest where inventory items are temporarily removed)
7. "Toggle realism mode." - (Default OFF) If this is ON:
---Companions (except clones) will demand caps upon hiring and daily while they are following you.
----See pay scale, below.
8. "Reset Settings." Resets most settings and releases companions. Recommended before uninstall.

Realism Mode Pay Scale:
=======================
This only applies if you have turned realism mode on in the setup menu.
Pay scale is based on your alignment vs. NPC's alignment.
If NPC's alignment is equal to yours, their cost is 5 caps upon hiring and per day.
Cost increases for each level of alignment difference.
Let's say your Karma is 750 or above (So you have an alignment of Very Good):
NPC Alignment == Daily Pay
Very Good == 10 caps
Good == 20 caps
Neutral == 40 caps
Evil == 80 caps
Very Evil == 120 caps

Selecting Your Companions:
=========================
Almost any NPC in the game can be your companion with this mod. The way of doing this is different
-depending on whether or not you are using NVSE:
Non-NVSE Users:
1. When you are ready, select "I'm ready to pick a companion." from the Setup Menu
---Note that while this is active you will not be able to talk to an NPC
2. Activate the NPC you would like to be your companion with the activate key (Default: E)
3. Select "Be My Companion" from the menu.
NVSE Users:
1. Press the Companion Menu key you bound with the NPC in your crosshair.
---You will receive an error message if the NPC cannot be your companion.

Setting Up Your Companion:
=========================
Some NPCs really can’t hold their own in combat, so I have added a few measures to help with this.
If the NPC’s maximum health is low (less than 50% of player’s maximum health), you will be asked if 
-you want to increase their health. If you select “Yes”, their max health will be increased to 75% of 
-yours.
You will be given the option of training your companion in 2 skills. If you are making your clone your
-companion, you will instead be asked if you want to set your clone’s attributes to match your own. Select
-“Yes” to do so. Your clone’s Pip-Boy is removed. This is necessary for your clone to equip things you
-give them.

About Your Companions:
======================
Your companions will ignore friendly hits and crime*. They will never attack you under any circumstance, as
long as they follow you. In addition, a mechanism is in place to ensure your companions go
everywhere you go. If you go somewhere and they don’t show up, just wait a few seconds and they will.
You get a [Companion Locator] in the “Aid” section of your Pip-Boy, just in case. Using this will
-make all of your companions appear at your side.
Companions will use stimpaks if they have them and are hurt, so feel free to share.
Companions can't be killed but can be knocked unconscious.
Your companion's limb conditions are restored upon end of combat.
*Accidentally striking your companion may cause you to gain faction infamy if they are in a faction.
*Your companion may initiate combat with enemies of their faction, and may be attacked at the entrance
-to the strip by the securitrons.

Activating the Companion Menu:
==============================
Non-NVSE Users:
1. You will have the [Companion Menu] item in the Aid section of your Pip-Boy
2. Assign the item a hotkey (hold a number key 1-8 [except 2] and left-click on the item)
3. Exit your Pip-Boy and press the hotkey.
---If you have more than one companion, you will need to pick a companion.
---If the companion is not close by, you will be asked if you want to move them to your location.
NVSE Users:
1. Press the key you bound at any time (Or use the above method)
---If one of your companions is currently in your crosshair, the menu for that companion will appear.
---If nothing is in your crosshair and you have more than 1 companion, a menu will appear asking
----which companion you want to activate the menu on.
---If nothing is in your crosshair and you have just 1 companion, that companion's menu will
----appear.
---If the companion is not close by, you will be asked if you want to move them to your location.

The Companion Menu:
===================
This menu lets you manage your companion's inventory, change their combat style, and more.
1. Make This Your Hangout - Set a hangout spot for the companion to go to when you want them to
2. Go To Your Hangout and Wait - The companion will teleport to their hangout spot and, well, hang out
3. Change Follow Distance - Choose whether you want your companion to follow you closely or from farther away
4. Change Combat Style:
---Default – Companion may use both melee and ranged combat
---Ranged – Companion will use ranged weapons exclusively
---Melee – Companion will use melee weapon or unarmed combat exclusively
---Sniper - Companion will shoot from a greater distance, using ranged weapon exclusively
5. Use a Stimpak - Your companion will use a stimpak. This option only appears if they are hurt
6. Guard This Location / Stop Guarding - Your companion will stay put until you choose otherwise
7. Manage Equipment - Add and remove items to and from your companion’s inventory
---(Note for NVSE users): If using on clone, menu appears twice. Use the first time, exit the second time
8. Show Stats - Display companion’s S.P.E.C.I.A.L. points followed by Skills
9. Stop Following Me, You're Fired - Your companion will return to where you first found them.
---Or, you can select for them to stay at the Lucky 38
---All of their modified attributes will be restored and any special weapons you gave them will be removed
10. Have a Cigarette / Stop Smoking - Pick whether you want your companion to smoke (doesn't work on clones)
11. Copy Player Stats to Clone (Player Clone only) - Duplicate your current stats and skills over to your clone
12. Add Special Weapons - Choose 1 ranged weapon and/or 1 melee weapon to give your companion.
---These weapons will not show in their inventory. Ranged weapons in this list do not require ammo.
13. Remove Special Weapons - Removes the added weapons
14. Train Your Companion (Not Player Clone)
---Opting for this allows you to pick 2 of the NPC’s skills which are then set to match your own skill.
---Choose from Guns, Energy Weapons, Explosives, Medicine, Melee Weapons, Repair, Survival, Sneak,
----or Unarmed

Giving Orders (NVSE)
====================
-HOLD DOWN the Targeting key (Default: L Shift), and tap Attack.
-Hold Targeting Key, center in on target, and tap Attack. If the target is invalid (i.e. you target nothing or
--target a teammate) an error message will display. The crosshair does not have to be bracketed for a target
--to be valid. You can try targeting anything.
--A valid target will highlight for one second and the message "TARGETING ..." will display on the screen
-If a valid target is selected, a menu will appear. If you have more than 1 companion, you will be asked which
--companion you want to give orders to (Companion 1-5, or All Companions)
-If the target is close, you will be warned.
-If the companion's view of the target is obstructed, you will be warned (If target is NPC or creature).
-Individual Companion Orders:
1. Attack Target
---Your companion initiates combat with the target NPC or creature.
---The target must be an NPC or creature for this option to appear.
2. Throw Grenade at Target
---Your companion will throw a grenade at the target (companion must have grenades in their inventory).
---Grenade is chosen with priority based on damage caused.
---Pulse Grenade - Target must be a robot. If companion has no pulse grenades, they will use another type.
---Plasma Grenade - 1st choice
---Frag Grenade - 2nd choice
---Incendiary Grenade - 3rd choice
---Dynamite - 4th choice
---Long Fuse Dynamite - 5th choice
---If the companion has no grenades, this option will not display.
3. Fire Weapon at Target
---If your companion is using an automatic weapon, they will fire 20 rounds.
---Otherwise, your companion will fire one round at the target.
---Make sure their path to the target is clear.
---Confirm menu will appear if target is out of range of the weapon.
---If the companion does not have a ranged weapon equipped, this option will not display.
4. Lay a Mine Here
---Brings up a menu for you to choose the type of mine (companion must have mines).
---*The target doesn't matter, the companion will throw the mine about 4 feet in front of them.
---The mines can be set off by neutral or enemy NPCs.
---If the companion has no mines, this option will not display.
-If you're giving orders TO a creature that is your companion, options 2-4 will not display.
-Otherwise:
#2-#4 may initiate combat with the target and their friends if:
a. the target is an NPC or creature AND
b. the target is hit AND
c. the companion who hit the target is detected by the target AND
d. the target does not have a "friend" disposition
#2-#4, if an enemy is hit, will:
a. cause surrounding enemies to search for you AND
b. if the enemies detect you or your companion(s), they will attack
-All companion Orders:
1. Attack Target
---All companions will initiate combat with the target NPC or creature.
2. Fire Weapon at Target
---All companions with a ranged weapon equipped will fire at the target.
---Companions will fire regardless of objects or persons in between them and the target.

================
Additional Info:
================
1. This mod adds companion functionality via quest / effect scripts and menus.
---The companion wheel will NOT work because that is based on dialogue
---When entering a new area or loading a game, a companion may start to run away briefly, but will come back.
2. Companion may follow you into an area after being told to wait
---Script will teleport them back to where they are supposed to be after a few seconds
3. If the companion belongs to a faction, friendly fire might cause you to gain infamy with that faction.
---There are console commands such as setreputation that can correct it

===============
Requirements:
===============
Fallout New Vegas

===============
Recommended:
===============
NVSE (New Vegas Script Extender)

===============
Install:
===============
1. Extract the .esp file from the archive.
2. Copy files to (install folder)\Fallout New Vegas\Data\
3. Start Fallout New Vegas Launcher, click 'Data Files', place a checkmark beside the .esp file.
---Or use a mod manager, I recommend Vortex

===============
Upgrade:
===============
1. Install new files over old files.
2. Launch Fallout New Vegas.
---Or use a mod manager, I recommend Vortex

===============
Un-Install:
===============
1. From the game, left-click on the [Companion Setup] item in the "Aid" section of your Pip-Boy.
---Select "Reset Settings" then save your game.
2. Deactivate the mod in Vortex (or another mod manager)
(if not using a mod manager)
1. From the game, left-click on the [Companion Setup] item in the "Aid" section of your Pip-Boy.
---Select "Reset Settings" then save your game.
2. Start New Vegas Launcher, click Data Files, uncheck the .esp file.
3. Delete the file: Fallout New Vegas\Data\Groovy Companions.esp

===============
Compatibility:
===============
This mod may conflict with other mods that allow any NPC to be a companion.

===============
Bugs/Issues:
===============
Game may crash if you uncheck the .esp and load a saved game in which you were using this mod.
This is a PERK issue. If you are using NVSE, you don't have anything to worry about, but
-everyone else needs to Follow the "Un-Install" instructions.
When targeting an NPC, the "Fire weapon at target" command doesn't work well when the target
-is sitting or lying down. Shots tend to go above the target's head.
Training a creature in skills does not work right. training them in 1 skill will also
-raise several of their other skills.
If you are not using NVSE, Your clone will not always equip what you give them.
-To force them to equip something:
1. Go into console and click on your clone
2. Type “showinventory”
3. Choose what you want them to equip
4. Type “equipitem XXXXXXXX 1” – replace the X’s with the Item’s ID
5. Repeat until everything needed is equipped
---Just get NVSE.
Clone animation problems:
Activate the optional .esp "Groovy Companions - Clone Animation Fix" to fix some of these problems.
1. If your clone is hanging out (sandboxing) and they use furniture, and you are in 1st person mode,
---your clone will do the 1st person animation (this will turn them sideways and may make them
---disappear from view).
2. When performing VATS melee attacks, your clone will also perform the attack animation.
3. Your clone is prevented from doing several animations that other NPCs can do, including
---sleeping, picking up objects, smoking, eating, weapon animations, and more.

===============
History:
===============
1.07 - Bug Fix / Misc
-Giving orders to attack to all companions will initiate combat appropriately
-Targeting script now uses ObjectUnderReticle rather than GetCrosshairRef
--No need to modify iactivatepicklength now since this function is more intuitive

1.06 - Misc
-Increased follower dues 2x
-Minor usability changes
-When ordering a companion to attack a neutral, they should now start combat appropriately
--The target also starts combat with the companion, even though they may remain neutral to player

1.05 - Added function
-Former companions staying at the Lucky 38 can be sent back to their original location
--NVSE users - press the Companion Menu key with them in your crosshair, it will be the third option
--Non-NVSE users - Open the companion setup menu and select "I'm ready to pick a companion",
---then activate the NPC, select "Be my Companion". It will be the third option in the menu
---if we can't teleport them (they were at L38 before v1.05), they should walk/run to their original location

1.04 - Bug Fix
-Companions /shouldn't/ run from combat (Confidence 4, Aggression 1)
-If you drop [Companion Locator], it will be re-added
-Bumper sword weapon is now removed when companion is fired, if it was added
-Allowed more leniency for companion to move around when guarding, before being teleported back
-Manage Equipment is now on the first page of the Companion Menu, Fire Companion is now on next page

1.02 - Bug Fix
-"Toggle Realism" now causes daily companion cost to be set correctly if you already have companion(s)

1.01 - Bug Fix
-Fixed issue where selecting "Reset Everything" didn't remove clone
--Also removed script packages from companions here so they will no longer follow player

1.0 - Initial Release:
-Ported from "Groovy Followers" (https://www.nexusmods.com/fallout3/mods/8927)
-Set when mod activates after character generation
-More instruction within game (Notes added, additional message boxes)
-Changed skills to match NV skills
-Changed grenade selection (giving orders - NVSE) to match NV "grenades"
-Changed unique companion weapons to an assortment of NV weapons
-Reworked Hangout/Guard/Targeting
-Restore limb condition of companions after combat end
-Ensure combat style is set
-Enabled using this on any creature
-Additional code to make sure the companion is doing what they're supposed to
--They may follow into another cell/fast travel with you when they are supposed to wait
---Script then teleports them to where they are supposed to be
-Rewording of messages
-The companion wheel cannot and will not work
--It is dialogue driven, meaning the specific NPC must have dialogue for the functions
-Added functionality to send companion to the Lucky 38 when fired
--For non-clone and non-creature

===============
Contact:
===============

Questions? Comments? Suggestions? Free money?
DraykCannon at TheNexusForums

===============
Credits:
===============
All work by DraykCannon
Thanks to:
Obsidian/Bethesda for creating Fallout New Vegas
Koupoable for porting The Groovatron to New Vegas

===============
Tools Used:
===============
GECK
NVSE
FNVEdit
bae
Notepad++

===============
License/Legal:
===============
As Always, with any Mod, use at your own risk.
Do not upload to other sites.