I've seen a few mods that add fire damage to the flamer, cryo damage to the cryolator, and even one mod that tried to fully integrate those damage types and their corresponding resistances into the game. I didn't think any of them went far enough, so I decided to go ahead and take a crack at the idea myself. Not only did I change those weapons, and a few others, but I also went and added resistances to pretty much every non-human NPC in the game. A complete(ish) changelog will be located at the bottom for more information.

This mod requires the unofficial patch, which in turn means you'll need all DLC in order to use it. I did this for a few reasons:

• You should be using the unofficial patch anyway
• I think the DLC is worth it, for the most part
• The glowing mutant hound doesn't glow without the unofficial patch
• Enraged fog crawlers have 4000 DR without the unofficial patch
  

So, rough overview of this mod: Flame weapons do fire damage, freezing weapons do cryo damage. The Incendiary and Freezing legendary mods have been buffed and I've added some new legendary armor effects that will add elemental protection. Additionally, most armour types will provide some combination of cryo/fire resistance. So far, the only exceptions are raider and trapper.

Electrical Damage also sits unused in the files, but I left it alone because it seems to just add on to base Energy Damage. Same story with Electrical Resistance.

Also included is an optional patch to add some additional synergy between this and Cut Weapon Mods Restored by frogs345. It goes without saying that you'll need both my mod and theirs in order to use the patch.

V2.1 CHANGELOG:

• A few alpha mongrels had no resistances due to Bethesda not setting all of them up to share stats with regular mongrels. I've fixed this and made it more consistent.
  

V2.0 CHANGELOG:

• Fixed typo in Freezing effect description.
• Lowered damage of Freezing, Incendiary, and Plasma-Infused from 25 to 15.
• Elder Maxson's coat now has 50 ER and 25 CR and FR.
• Trapper armour has been given CR and FR equal to two-thirds of its ER, rounded to the nearest whole number where appropriate.
• DLC02 mythic deathclaws now have CR and FR.
• The unused young yao guai in Nuka-World now has CR and FR, just in case.
• Gazelles now have CR and FR
• Long johns provide 3 CR.
• Super mutant armour now provides CR and FR equal to half of its ER. Expect super mutants to be a bit tankier against flamers and cryolators.
  

V1.93 CHANGELOG:

• Synth gorillas and ghoulrillas now have PR, CR, and FR equal to half their ER.
  

V1.92 CHANGELOG:

• Nukalurk queen, mirelurk queen, and ancient behemoths have had their levels reset to their fixed vanilla numbers.
  

V1.91 CHANGELOG:

• Molotov cocktail explosion damage has been reduced from 150 to 100 in line with cryo explosions.
  

V1.9 CHANGELOG:

• Spike armour has been given 10 CR and FR.
• Helmeted spike armour has been given 12 CR and FR.
• X-01 thermal paint now correctly provides CR instead of FR.
  

V1.8 CHANGELOG:

• Changed various effects to use cryo or fire resistance where appropriate. Most notably, oil traps will now deal fire damage.
  

V1.7 CHANGELOG:

• Suffolk County Charter School ghouls now have cryo and fire resistance.
  

V1.6 CHANGELOG:

• Corrected Automatron cryo arms to do cryo damage instead of fire.
  

V1.5 CHANGELOG:
ARMOR

• Leather: Now provides cryo resistance equal to that of its base energy resistance.
• Combat: Now provides cryo and fire resistance equal to half of its base energy resistance.
• Metal: Now provides fire resistance equal to that of its base energy resistance.
• Synth: Now provides cryo and fire resistance equal to that of its base energy resistance.
• Robot: Now provides cryo resistance equal to that of its base energy resistance.
• Marine: Now provides cryo and fire resistance equal to that of its base energy and ballistic resistance.
• Operator: Now provides cryo and fire resistance equal to that of its base energy and ballistic resistance.
• Disciple: Now provides cryo and fire resistance in between that of its base energy and ballistic resistance.
• Pack: Now provides cryo and fire resistance equal to that of its base energy and ballistic resistance.
• Railroad armored coats: Now provide cryo and fire resistance equal to that of its base energy resistance.
• Courser uniform: Now provides cryo and fire resistance equal to that of its base energy resistance. 
• Cage armor: Now provides 20 cryo and fire resistance.
• Helmeted cage armor: Now provides 22 cryo and fire resistance.
  

POWER ARMOR

• Frames: cryo and fire resistance equal to that of its energy and ballistic.
• General: All power armor types now feature cryo and fire resistance equal to half of their base energy resistance, to a minimum of 15. Upgrades from A to F also increase cryo and fire resistances, and winterised and thermal paints increase cryo and fire resistance respectively.
  

NPCS

• Mr Handy: Flamer damage has been increased from 1 back to 20.
  

v1.0 CHANGELOG:

LEGENDARY EFFECT CHANGES

• General: All elemental buffs have been halved from 50 to 25.
  

• Incendiary: Changed damage bonus from 15 to 25, as intended.
• Poisoner's: Applied a base 25 poison damage boost in addition to poison DOT.
• Plasma-Infused: Buffed base damage bonus from 15 to 25.
  

WEAPONS

• Flamer: Previous 3 energy damage has been replaced with 3 fire damage.
  

NPCS

• Glowing mutant hound: PR, CR, and FR have been raised from 35 to 45.
• Infected rad rat: CR and FR have been raised from 40 to 50.
• Plagued rad rat: CR and FR have been raised from 70 to 90.
• Yao guai: PR has been raised from 60 to 65 while CR and FR have been raised from 100 to 110.
• Shaggy yao guai: CR and FR have been raised from 115 to 125.
• Glowing yao guai: CR and FR have been raised from 125 to 135.
• Albino yao guai: CR and FR have been raised from 135 to 145.
• Rabid yao guai: CR and FR have been raised from 150 to 155.
• Dusky yao guai: PR has been lowered from 125 to 110.
• Yao guai ghoul: PR raised from 60 to 85 while CR and FR have been raised from 95 to 120.
• Irradiated yao guai: PR raised from 70 to 105 while CR and FR have been raised from 100 to 140.
• Mirelurk: PR and CR have been raised from 90 to 100.
• Mirelurk razorclaw: PR and CR have been raised from 120 to 140.
• Mirelurk killclaw: PR and CR have been raised from 125 to 160 while FR has been raised from 60 to 90.
• Glowing mirelurk: PR and CR have been raised from 150 to 185.
• Bloodrage mirelurk: PR and CR have been raised from 160 to 220.
• Glowing angler: CR and FR have been lowered from 160 to 145.
• Albino angler: CR and FR have been lowered from 190 to 180.
• Venomous angler: CR and FR have been lowered from 230 to 220.
• Protectron watcher: CR and FR have been raised from 20 to 40.
• Protectron guardian: CR and FR have been raised from 25 to 55.
• Nukalurk: CR and FR have been lowered from 320 to 185. Not sure why I had it set so high, to be honest.
• Siege breaker sentry bot: CR and FR have been raised from 110 to 115.
• Annihilator sentry bot: CR and FR have been raised from 135 to 140.
• Annihilator sentry bot mk II: CR and FR have been raised from 80 to 90. Yes, this sentry bot has lower stats than the previous one. No, I'm not sure why. I might change this in an update. We'll see.
• Bubble turret 02: CR and FR have been raised from 15 to 25.
• Bubble turret 03: CR and FR have been raised from 25 to 45.
• Bubble turret 04: CR and FR have been raised from 45 to 70.
• Tripod turret 02: CR and FR have been raised from 15 to 20.
• Tripod turret 03: CR and FR have been raised from 25 to 35.
• Tripod turret 04: CR and FR have been raised from 30 to 45.
• Vertibird 02: CR and FR have been lowered from 100 to 97.
  



v0.9 CHANGELOG:

LEGENDARY EFFECT CHANGES

• Incendiary: Buffed base damage bonus from 15 to 50. Unused incendiary bullet flesh impact sound set applied.
• Freezing: Buffed base damage bonus from 15 to 50.
• Poisoner's: Modest buff of 3 poison damage over 10 seconds to 5 poison damage (subject to further tweaking).
  

NEW LEGENDARY EFFECTS

• Fireproof: +25 Fire Resistance.
• Hazmat: +25 Radiation Resistance
• Insulated: +25 Cryo Resistance.
  

NPCS

• General: Almost every non-unique and non-human NPC has been given Fire and Cryo Resistance; some who did not previously have Poison Resistance have been given that as well.
• Ancient behemoth: Now scales in level with the player.
• Mirelurk/nukalurk queen: Now scale in level with the player.
• Radrat: Now has 35 Energy Resistance and 0 Endurance instead of 15 Energy Resistance and 35 Endurance.
• Fireman protectron: Now deals cryo damage instead of energy.
• Mr Handy: Flamethrowers now do fire damage instead of energy. Brought middle thrower in line with left and right throwers (subject to change based on testing/feedback).
  

WEAPONS

• Cryolator: Now deals cryo damage instead of energy.
• Flamer: Now deals fire damage instead of energy (Note: For reasons I have yet to determine, the flamer still retains some small energy damage).
• Cryo grenade: Now deals a flat 100 cryo damage bonus.
• Cryo mine: Now deals a flat 100 cryo damage bonus.
• Molotov cocktail: Now deals a flat 150 fire damage bonus (subject to further tweaking).
• Shishkebab: Now deals bonus fire damage instead of energy.
  

WEAPON MODS

• Shishkebab: Damage mods now add fire damage instead of energy.
• Flamer: Damage mods now add fire damage instead of energy.
• Power fist: Heated coils now add fire damage instead of energy.
• Sledgehammer: Heated mods now add fire damage instead of energy.
• Super sledge: Heated mods now add fire damage instead of energy.
• Paddle ball: Fire ball mod now adds fire damage instead of energy.
  

ARMOR MODS

• General: All Asbestos Lining mods now add Fire Resistance instead of Energy Resistance.