In Melee the following franchises had 2 or more stages (excluding past stages):
Mario (4)
Donkey Kong (2)
Legend of Zelda (2)
Metroid (2)
Yoshi (2)
Kirby (2)
Star Fox (2)
Pokémon (2)
F-Zero (2)
Earth Bound (2)
In Brawl the following franchises had 2 or more stages (again, past stages excluded):
Mario (4)
Donkey Kong (2)
Zelda (2)
Metroid (2)
Pokémon (2)
In Brawl we saw more franchises get 1 stage, we saw more franchises (including 3 without character representation; the DS/Nintendo franchise, Hanebow, and Animal Crossing) getting stages, but we also saw less stages with one stage. I think in SSB Wii U we will see more of what happened in Melee, but I also wouldn't put it past Sakurai to include up (along with 4 or more new Mario stages) to 3 new Zelda, Pokémon, and possibly even Donkey Kong stages.
Overall, this is my 2 or more stage predictions for Smash Wii U (again, past stages excluded):
Mario: 5; I see a Princess Peach stage happening, Bowser's Castle, a new Luigi's Mansion, and 2 Mario stages (Metal Mario Stage from Smash 64... PLEASE!).
Donkey Kong: 2; possibly one from DKC1 or 2, and probably one from DKC Returns
Zelda: 3; 1 from one of the 2 new handheld Zeldas, 1 retro, and 1 from Skyward Sword
Metroid: 2; probably one or both are from the Metroid Prime Trilogy and maybe something from Other M
Kirby: 2; one from Epic Yarn, and another classic Kirby stage; King Dedede's ring?
Pokémon: 3 or 4; A new Pokémon Stadium, a Kanto location, the Elite Four area from Black/White, and something from Kanto or Hoenn.
Fire Emblem: 2; really we have had 1 unspecific stage. We really need specific Fire Emblem locations!
Metal Gear: 2; Kojima will probably make one, Sakurai another. My guess is something from MGS3 or 4.
Sonic the Hedgehog: 2; because we all want to see mroe Sonicz! Angel Island and Emerald Hill Zone ougtha do.