Training Ground looks bland, and I feel that the weapons are clumped instead of evenly spread. Also, put something at the end of that hallway so someone might actually go back there.
I didn't explore Shadow Mansion very long, but it's very difficult to jump over to reach the Eddie. Think there may be a spike glitch. All for now.
Large Desert is simply too big to be enjoyable, and weapons also seem to be scarce here.
Splash Castle would actually do great as Splash-Woman's stage--with modifications. I'd change the tiles to the various pipes and such seen in her stage, and replace Crystal Eye with Laser Trident (if it exists yet) .
Also, the edges of the Light sign are Airman.
Shrinking Lab is an okay stage, but it feels odd because you can't shoot out onto the normal-sized area. The bots can see you, you can see them--you just can't hit each other. Either fully box in the area, or figure out how you could do this.
Duel Arena--actually, no comment on Duel Arena. Never have I seen such a balanced room with so many broken weapons.
Thermal Plant has too many powerful weapons. Trolling Cutter, Youmad Cracker, MIRROR BUSTER...do you expect to be housing the entire troll army here?
Also, for some reason, Eddie keeps giving me Centaur Flash. I'm not complaining, but still.
Training grounds is meant to be bland, it isn't for fighting but training
The Eddie thing isn't a glitch it's one of the many traps.
Shriking Lab, was just a small gimmick stage I made in like half an hour. If you want to try and fix it go ahead.
Duel arena was one of my better ideas, just you and your opponent and a variety of different weapons.
Thermal Plant was my first attempt at a stage
Large desert, is meant to be large and weapon scarce.
As for Splashwoman I agree I just don't have luck putting in custom tiles, also my original plan was to put Lazer Trident in the place of crystal eye, but I couldn't fine one.

The air man parts are left intentionally.
Do not know why Eddie keeps giving you that, maybe you're just lucky? O.o