Available characters as of V3Beta4 (use full name in prompt):
Amy Rose
Barry the quokka
Big the cat
Blaze the cat
Bunnie Rabbot
Charmy the bee
Cosmo the seedrian
Cream the rabbit
Eggman
Espio the chameleon
Fiona Fox
Honey the cat
Hershey the cat
Infinite the jackal
Jet the hawk
Jewel the beetle
Julie-Su the echidna
Knuckles the echidna
Lanolin the sheep
Lien-Da the echidna
Lupe the wolf
Marine the Raccoon
Metal Sonic
Metamorphia
Mighty the armadillo
Mina Mongoose
Mobian ______ (Original characters in sonic style basically!)
Neo Metal Sonic
Nicole the Lynx
Rouge the bat
Ray the flying squirrel
Rosy the rascal
Sage
Sally Acorn
Scourge the hedgehog
Shadow the hedgehog
Silver the hedgehog
Shade the echidna
Sonia the hedgehog
Sonic the hedgehog
Starline the platypus
Sticks the badger
Storm the albatross
Surge the tenrec
Tails the fox
Tekno the canary
Tangle the lemur
Tikal the echidna
Vanilla the rabbit
Vector the crocodile
Wave the swallow
Whisper the wolf
Zoey the fox
Zeta the echidna
USE:
The model uses Danbooru tags similar to anime models. I would not recommend just generating a character with no follow-up prompts as the results won't look very good. A good negative prompt also helps greatly.
Limitations:
Some characters generate less consistently. This problem will hopefully be resolved in the full release of V3 as I gather more training data.