If Fountain of Dreams was in, I'd cry tears of joy.
Not exactly a stage but I wish transformations were legal in Pokemon Colosseum so that it'd be like Dracula's. Don't make it like Melee's Stadium though lol. I like it, but if jank can be reduced, it should be reduced.

In terms of Sonic stages, City Escape and The A.R.K. are my top choices, although a flooded Station Square could be cool.

Well, besides wishing all removed stages to come back, I would like to see Fountain of Dreams coming too.
When speculating, I think we can get Icy Mountain, even without Ice Climbers in the game.
The same goes to Umbra Clock Tower, I would like to see it even without Bayo.
Waluigi still doesn't have a stage, so I speculate a stage based on Waluigi Pinball.
There are always stages without character representation in smash, and I thought that including a bubble bobble based stage would be cool.
We have enough representative stages for the sonic series, but if Knuckles or Shadow were about to come, Pumpkin Hill could be a nice Knuckles stage and Final lizard (on the spaceship) would be a cool Shadow's stage too.

- Shadow Moses Island
- Boxing Ring
- Waluigi Pinball