2/3 of them are references to

Sonic's Concept and is also a Skin in Sonic Superstars Cream's Debut (Though inconsistent looks)

A former 90s rival's (A red capped plumber guy) recent 3D platformer since 2017

The "Big Green Man" (Guest) teaser.

I'm taking you down like its 1998/1999!

Basically

Valgallah's Cream's "Chao Force" Super

Command is

D,DF,F X+Y

Sumin didnt just make some characters But also sandbag (Though bare bones)

Act Music as Rounds? (may not apply to every stage)

(Advance 1) Angel Island Zone.

Originally for Infinite Battle Now retooled

Despite being Water (Or Mutated Chao) slime sounds

That Hover Move.

It's like the OG game but less stiff.

(coming some time soon or something.) The 1st Sonic Battle Redux arcade Run: Sonic.