Hmm, guess here would be the best place to put this. Made a post on another forum about stage legality, so I'd figure I'd throw it here for discussion's sake.
Guesswork after Post-Direct footage:
Neutral:
-Battlefield
-Final Destination/Omega Stage Forms
-Smashville
-Town and City
-Lylat Cruise
-Miiverse
Counterpick/Neutral?:
-Big Battlefield (Stage may be too large to be a starter.)
Counterpick:
-Delfino Plaza
-Halberd
-Castle Siege
-Skyloft
-Pilotwings
-Wuhu Island
Banned/Counterpick?:
-Kongo Jungle 64 (Banned in Melee singles, will probably be extensively tested.)
-Mushroom Kingdom U (Good stage layout, but the hazards look like a big problem.)
-Wooly World (Stage transition and moving platforms may too heavily favor aerial-based characters.)
-Wrecking Crew (Platform transitions don't seem to damage/affect gameplay, but upper platforms may be too close to upper blast lines.)
Banned:
-Kalos Pokemon League (Stage frequently changes form, and all forms have constant and disruptive hazards. Torches, swords, water stream/walkoffs, and Rayquaza.)
-Wii Fit Studio (Permanent walk-off stage.)
-Gamer (Centralizing(?) hazard with the mother, which will inevitably disrupt gameplay.)
-Orbital Gate (Seems to heavily advantage aerially inclined characters akin to Rainbow Cruise.)
-Jungle Hijinx (Stage gimmick will probably allow a lot of stalling attempts or back-and-forth that slows gameplay to a crawl.)
-Coliseum (Permanent walk-off with high-reaching platforms.)
-Garden of Hope (Aristocrab swarm.)
-Pokemon Stadium 2 (Frequently disruptive/game changing transformations.)
-Mario Galaxy (Permanent walk-off stage.)
-Mario Kart 8 Circuit (Seems to have overly powerful car hazards and a lot of wall-bouncing.)
-Norfair (Platforms are small, constant hazards, instant death hazard that shifts gameplay focus.)
-Yoshi's Island (Permanent walk-off stage, caves of life with the flipping blocks.)
-Skyworld (Impassable platforms that can cause early gimps, disrupt recovery, and allow for caves of life.)
-Temple (Stalling, caves of life on the mid-lower half of the stage.)
-Bridge of Eldin (Permanent walk-off stage, huge size allows for camping, incredibly disruptive stage hazards.)
-Port Town Aero Dive (Cars hit hard and KO very early, main platform has no grabbable ledges.)
-Onett (Permanent walk-off stage, powerful and random car hazard.)
-Luigi's Mansion (Caves of life in impassable platforms, circle camping ala Temple possible with stage design.)
-Mario Circuit (Permanent walk-off stage, powerful car hazard.)
-Great Cave Offensive (Literally everything)
-75m (Only stable, large platforms are walk-off areas or are littered with hazards. Massive size allows for stalling.)
-Boxing Ring (Permanent walk-off stage, camping on lights against characters with bad jumps.)
-Palutena's Temple (Stalling, probably has caves of life like Hyrule Temple, etc.)
-Dr. Wily's Castle (Yellow Devil stage hazard completely shifts gameplay focus to it rather than PvP, can interrupt gameplay, etc.)
-Pyrosphere (Centralizes gameplay around Ridley, provides ludicrous advantage for people who get him, other stage hazards seem to exist, etc.)
-Pac-Land/MS Paint Land (Seems to be a sidescroller, making it a permanent walk-off stage.)
-Windy Hill (Irregular design, springs on side that will disrupt recovery, sides of stage are very close to blast zones, and top of stage seems relatively close to the upper blast zone.)
-Guar Plain (Huge size and irregular platform placement that advantages aerial characters. Metal Face is an additional point against, much like Ridley and Yellow Devil.)
Just my guesses here. Seems like we'll get a sizable amount of tournament-legal stages this time around.