Yeah, that stage was banned from the start dude. Somebody tried to have it at a tournament and after like one tournament it was IMMEDIATELY gone tri-state and everyone else was like, "Why the hell did you even have that on?"
—D1's (maybe?) correct reminiscence of PS2's legality, 
Once upon a time Pokemon Stadium 2 had a senpai named Pokemon Stadium. Pokemon Stadium was loved among the competitive Smash Bros scene because they banned so many stages that they had to hold on to what remained, even if that senpai was considered kinda campy. Then Brawl, and subsequently Stadium 2, showed up and got no sympathy from anyone except people who thought PS2 could be useable like PS1 senpai. This was a larger minority back in the day, but now while the number of competitives in support haven't changed, the number of new players who joined and immediately went against has grown to the point where a counter-pick stage was banned. (Better than one going from neutral to banned at least )
Arguements for each formEdit
Neutral form is good, it alone is in Project M.
The treadmills force players to either limit their arena to the center or camp on ledges until it wears off.
The shrunken arena allows for characters who fight at a close range to shine.
The floatyness... it hurts... IT BURNS!!!!
Certain characters work best in certain stages. Good aerials are a must in Battlefield, and FD gives an edge to projectile users. Characters with more weight to touch the ground, as well as floatier characters with good air game shine in this portion.
That is a similar problem Stadium 1 has for all it's forms.
Too much movement because of sliding. This also increases tripping because you move more to get less in another direction.
This isn't Brawl. The added movement allows for better technique including an easier-to-use DACUS.