Eh well...here's my opinion on stage bans:
Luigi's Mansion - Have no real problem with this stage, as both characters can use the low ceiling to their advantage and it can help with "camping" a bit too.
SkyWorld - No way should this be legal. The fact that some characters cannot recover, even with that moving platform at the bottom should be a big enough sign of ban worthy.
Pokemon Stadium 2 - I'm leaning towards ban on this one, simply because it does alter gameplay quite a bit at points, but meh, I personally don't have a problem with it.
PictoChat - This is another FD like stage with random stage hazards. I can't say I'm aganist it, but I'm not for it either.
Elecktroplankton - This stage doesn't seem bad at first, but It really is. Hittable terrain can mess up button inputs and the fact that if you fall even accidentlly on rippling water it's instant death is BS. It's almost like that fish on Summit, except you can't see it coming. I vote for ban.
Onett - NO. Although the borders allow for some easier kills and less lengthly matches, the fact there are four walls and two walk off sides make this almost like a permanent version of Delfino Plaza.
Norfair - I'm sorry, but I personally believe this stage SHOULD be banned. Main reason being...it's not really a stage. More often then not, the fight is taken to a SINGLE platform, so in a sense it's no better then any Create-A-Stage, except this one has quite a number of stage hazards.