Make sure that the player hitboxes match the size of the character that you're seeing on screen
The hitbox for player 1 in particular here appears to be taller than the actual sprite--which can be felt when you jump into a ceiling and you feel yourself crash into it before your player appears to actually collide with it
Otherwise shots might look like they're missing but actually hit and people will get mad lol
I'd also try to play around with the layout of the platforms on the map a little more, and consider using both solid platforms and jump-thru platforms; right now it's kind of like wrestling through a maze of solid objects rather than dancing around cover from your opponent
Oh and use tiled backgrounds or similar for the textures on the platforms; right now you can see that it's just one sprite that's been stretched and squashed a bunch of different ways. Tiling a texture instead of distorting a sprite will help it to look a lot nicer I think