I say that different animals of mimics have different effects, you can start seeing frog or reindeer mimics instead of just gorillas.
FROG MIMIC : Jumps farther but deals less damage
CAT MIMIC : Able to climb on walls.
DOG MIMIC : Makes a barking sound to attract other monsters when at low hp.
REINDEER MIMIC : Able to charge with their horns.
TURKEY MIMIC : Able to run around faster and making REALLY annoying noises when jumping.
Not that much to say but i just wanted to post a small idea.