I wish the robotmaster selection was more centered and away from the Push Start text. My ideal way would be to position them like a triangle around Megaman. Either that or move the Push Start text to the bottom with all that free space.
The color of the background tile set of Volt Man's stage during the outside sections clash with the foreground tiles. I wish they were darkened more like the underground portion, making it clear what is and isn't collideable geometry at first glance.
Dyna Man's stage is near perfect. No complaint other than the slightly bland boss arena.
Same for Sonic Man's stage, tho its boss arena is more varied. Still wish there was something visually interesting at the bottom of the pool. Also small enemies are a pain ;_;
Really cool what you have managed to make here.