As long as we're thinking of ridiculous and seemingly random characters for this game, I might as well. I kinda felt like being reminded of some old Zelda games anyway. So here's an attempt at a most over the top scenario roster [possible SPOILERS in list]:
-LoZ-
Link, Zelda, Ganon, Old Man (the hint guy), Darknut, Wizzrobe, Stalfos
-LoZ 2-
Dark Link, Horsehead, Error
-LttP-
Agahnim, Sahasrala, Link's Uncle, Blind the Thief
-LA-
The Shop Keeper,Marin
-OoT-
Sheik, Impa, Ganondorf, Rauru, Saria, Darunia, Ruto, Nabooru, Malon, Mido, Running Man, Dampe, Phantom Ganon, Twinrova, Iron Knuckle
-MM-
Fierce Diety Link!, Goron Link, Deku Link, Zora Link, Skull Kid, Odolwa, Mask Salesman, Tingle, King of Ikana, Zubora and Gabora
-Oracles-
Farore, Din, Nayru, Onox, Veran, Ralph, Ricky, Dimitri, Moosh, Maple, Subrosian, Pippin
-WW-
Tetra, King of Hyrule, Niko, WW Ganondorf, Medli, Makar
-Minish Cap-
Vaati (in Wizard form), Swiftblade
-TP-
Zant, Midna, Agitha apparently, Ashei, Rusl, Darbus or Dangoro, Purlo, Colin, Hero's Shade
-Phantom Hourglass-
Linebeck, Jolene
-Spirit Tracks-
Byrne, Cole, Phantom possessed by Zelda?
-SS-
Ghirahim, Groose, Fi, Demise, Koloktos, Scervo, Batreaux
-LBW-
Ravio, Hilda, Yuga, Gramps
That's just everyone I can possibly imagine... but honestly, my memory of several of the games is pretty fuzzy at this point. My (slightly) more grounded hopes for a roster:
Link, Zelda, Ganon, Dark Link, Agahnim, Sheik, Impa, Ganondorf, Rauru (with Kaepora transformation <.<), Saria, Darunia, Nabooru, Phantom Ganon, Twinrova, Fierce Diety Link, Goron Link, Deku Link, Zora Link (Those four maybe as one character that can transform?), Skull Kid, Mask Salesman, Tingle, Onox, Veran, Ralph, Tetra, King of Hyrule, Medli, Makar, Vaati, Zant, Midna, Agitha, Ashei, Hero's Shade, Linebeck, Byrne, Ghirahim, Groose, Fi, Demise, Ravio, Yuga
Ok, that's still too optimistic though. Prediction for final roster:
Link, Zelda, Ganon, Dark Link, Agahnim, Sheik, Impa, Ganondorf, Fierce Diety Link, Skull Kid, Tetra, Zant, Midna, Agitha, Hero's Shade, Ghirahim, Groose
The idea of Link with different items is cool though. I'm tired of listing stuff, but I'm guessing there are plenty that could create cool movesets.