Okay, time to talk about about the stages
CatRaccoonBL
and
Munomario777
mentioned.
Stages that most likely will be legal:
1. Battlefield
2. Final Destination
3. Smashville
4. Town & City
These four stages will work well even with hazards off.
Stages that have a high likelihood of being legal with hazards off:
1. Yoshi's Island SSBB (If stage hazard switch, SHS, removes Blarggwich the Support Ghost, then it should most likely be legal)
2. Pokémon Stadium 1/2 (If SHS removed transformation)
3. WarioWare, Inc. (Assuming minigames are gone it's probably legal as a counter-pick)
4. Lylat Cruise (If people want it)
Stages that largly depend on how hazard switch works:
1. Castle Siege (Even if it doesn't transform it might not be legal, though)
2. Wuhu Island (Might be too similar to Yoshi's Island SSBB)
3. Unova Pokémon League (Might be too similar to hazardless Pokémon Stadium though)
4. Kalos Pokémon League (Seems like a good counter-pick if SHS removes transformations)
5. Skyloft (If it doesn't transform)
6. Delfino Plaza (If it doesn't transform)
7. Yoshi's Island 64 (If the clouds are gone)
Other potentially legal stages:
1. Frigate Orpheon (It has a somewhat weird layout but it could potentially be a counter-pick)
2. Mario Circuit U (Depends on how it wirks with SHS and whether sharking works, but even then it's kind of similar to some other stages)
3. Fountain of Dreams (If it comes back)
4. Jungle Hijinx (Maybe, assuming the barrels are removed)
Probably banned (some of these could be used as alternatives to other, I suppose):
1. Great Plateau Tower (Cave of life)
2. Pokémon Stadium 1 with hazards on (It's not really a good stage in previous games, so why push it for this game?)
3. Port Town Aero Drive (It's basically FD?)
4. Duck Hunt (The tree is still an issue)
5. Midgar (It's basically Battlefield? Maybe as an alternative)
6. Dream Land 64 (Again, basically Battlefield)
7. Wily Castle (Basically FD)
8. Umbra Clock Tower (Either it's basically FD that makes people motionsick, or it's still banned because of the same reasons as in Smash 4)
9. Yoshi's Story (Maybe, it's very similar to Battlefield but the blast zones might be significantly different, so maybe legal as a counter-pick?)
10. Norfair (Easy to plank and camp for certain characters, and grounded options are severely limited. Poor Little Mac)
11. Halberd (If it doesn't transform at all, then it has walkoffs. Anyway, it's been banned before, it has several issues)
12. Arena Ferox (Some of the transformations are highly problematic)
13. Kongo Jungle 64 (Unless the blast zones are fixed it's still banned)
14. Gamer (Unless it chooses a good basic layout this is still banned)
15. Pyrosphere (It's far too big)
16. Reset Bomb Forest (The gap kills it, too easy to camp on, some characters would struggle too much to approach)
17. Prism Tower (Unless they change it, it has been confirmed to still have transformations, including a walk-off)
So, we have a minimum of 4 good stages, then we have a potential of up to 11 good stages dependingon how Stage Hazard Switch works, and potentially 4 more even. That gives us a maximum of 19 or so, although I think it's fairly likely many of these "maybe" will be "no" in practice.