This mod allows you to swap any enemy type of your choosing and change them to be another allowing to create yourself as hard a challenge as you want.
Other mods have already done some of these swaps I'm just trying to create a mod containing an entire collection of swaps.

Swaps contained in the ZIP:

Dogs to Female Zombie
Dogs to G-Adult
Dogs to Ivy
Dogs to Licker
Dogs to Palehead
Dogs to Poison Zombie
Dogs to Zombie
Dogs to Fat Zombie

Fat Zombie to Dogs
Fat Zombie to Female Zombie
Fat Zombie to G-Adult
Fat Zombie to Ivy
Fat Zombie to Licker
Fat Zombie to Palehead
Fat Zombie to Poison Zombie
Fat Zombie to Zombie

Female Zombie to Dogs
Female Zombie to Fat Zombie
Female Zombie to G-Adult
Female Zombie to Ivy
Female Zombie to Licker
Female Zombie to Palehead
Female Zombie to Poison Zombie
Female Zombie to Zombie

G-Adult to Dogs
G-Adult to Fat Zombie
G-Adult to Female Zombie
G-Adult to Ivy
G-Adult to Licker
G-Adult to Palehead
G-Adult to Poison Zombie
G-Adult to Zombie

Ivy to Dogs
Ivy to Fat Zombie
Ivy to Female Zombie
Ivy to G-Adult
Ivy to Licker
Ivy to Palehead
Ivy to Poison Zombie
Ivy to Zombie

Licker to Dogs
Licker to Fat Zombie
Licker to Female Zombie
Licker to G-Adult
Licker to Ivy
Licker to Palehead
Licker to Poison Zombie
Licker to Zombie

Mr X to Dogs
Mr X to Fat Zombie
Mr X to Female Zombie
Mr X to G-Adult
Mr X to Ivy
Mr X to Licker
Mr X to Palehead
Mr X to Poison Zombie
Mr X to Zombie

Zombie to Dogs
Zombie to Fat Zombie
Zombie to Female Zombie
Zombie to G-Adult
Zombie to Ivy
Zombie to Licker
Zombie to Palehead
Zombie to Poison Zombie

In order to use the mod you require Fluffy's Mod Manager and to drag the individual zip files containing each swap into the manager

For any Ghost Survivor specific enemies such as "Palehead" or "Poison Zombie" you will need to load into a level such as Kendo before you play the campaign.

Note: All enemies should now match their corresponding swaps, please notify me if they're not swapping to who they're detailed as.

Going through some testing it appears that if you replace standard Zombies with Fat zombies which don't have a lot of variants overall it will cause some of them to become invisible. This won't occur with standard or female zombies due to them having far more variations available.