Rash’s stage should somehow be the turbo tunnel because it is the most infamous stage from his game, the stage ultra would be knocking the character into the background and getting hit by Zits on his speeder bike as a reference to people always hitting one of the walls on their first time.
A neat reference would be as you battle you see Zits riding by and to explain why you see him over and over you can show him crashing and restarting the level since he will be moving not you.
If they were to do a Battletoads stage, personally I would like to see one from Battlemaniacs…if for no other reason because they are more visually appealing than any of the NES game’s stages.
The first stage would be a good one to use:
Sounds like something fans of the Dark Souls series could wrap their head around. Places like The Profane Capital or Brightstone Tselorda come to mind: A combination of architectural styles in a subterranean setting. Kinda like an underground version of Anor Londo or Dranleic Castle.