The new characters, abilities and systems we need have been listed down here:
Tails (flying, carry sonic abilities)
Knuckles (climb walls, glide ,abilities)
Amy? (Piko Piko hammer, sonic abilities)
Badniks (enemy that damages sonic ,system)
Eggman (change to death egg, or other bosses, Ability System)
Ring mechanic
Super peelout ability
eggman bosses Characters
Monitor system
Super form Character, can fly Ability
New sprites: Mania, 2, or 3
Maps!
Drowning mechanic
Run on water system
Springs mechanic
Working loops mechanic
Death mechanic
Compatible with mario mod, get damaged by mario enemies and kill them, and interacting with other mario stuff
Modern abilities (homing attack, bounce, boost)
Drop dash mechanic