that'd be amazing. i wish he was in, but like as everyone says megaman comes first.
his FS would be SLOOWW and everyone else moves slow but him, and maybe his special button does auto combos like it would in VJ1 when you spammed the punch/kick button. then he turns into regular joe for a minute or something, which means he wouldn't get a 3rd jump or something and moves really slow. and all a moves are nerfed.
his neutral b would definitely be one of those bombs that he gets in the game, or the V boomerang.
his smash b or up b could be that flying ship he rides. if it was his smash B it'd be something close to wario's chopper except it can shoot. it would probably be easier to break it though, and removes A moves from joe since i don't think his hands are exposed. smash B could also be a sped up dash using his superfast thing. kinda like falco/fox' except it sends foes horizontally. down b could be red hot kick and it'd be like falcon kick, except he bounces off the opponent or something.
sorry, i never do movesets and i didn't think i'd write that much. i just kept going and going.
PS there's probably a thread/movesets for him floating around.