Since the game recently came out, it's probably a good idea to get the tags ironed out ahead of time. There are five animatronic characters and each has an alternate "evil" version that is distinct from the characters. I'll list them and their evil names where I know them.

Animatronic name - Evil name - aliases

• Happy the Humble Heifer - Asset Joy - happy_(hhbf), evil_happy_(hhbf)
• Petey the Portly Pig - Asset Peter - petey_(hhbf), evil_petey_(hhbf)
• Charlie the Chillin' Chicken - Asset Chuck - charlie_(hhbf), evil_charlie_(hhbf)
• Sammy the Surly Salmon - Asset Samuel - sammy_(hhbf), evil_sammy_(hhbf)
• The Farmer - Asset Farmer(?) - farmer_(hhbf), evil_farmer_(hhbf)

The Farmer's evil counterpart is the only one I'm not completely sure about (hence the ?). The former four are easy to tell apart because they are monstrous and usually have gray pupils. Asset Chuck and Samuel don a more feral shape, Samuel has sharp angler teeth as opposed to Sammy's snaggle tooth. The farmer's the hardest one to tell apart, but if he's wielding a scythe, it's probably the asset. The farmer is already the villain of the in-universe franchise so he'll generally be evil

I started some wiki pages: https://e621.net/wiki_pages/39295

You can find tags with the tag search engine. Examples:
character tags containing 'humble'
tags containing 'hhbf'

The only tags that currently exist are happy_(happy's_humble_burger_farm) and the copyright tag happy's_humble_burger_farm.