Honestly, I see Sig (and pretty much the rest of the Fever-era and Puyo 7 characters) as Spirits. Actually, same goes for the Madou-era characters as well.Sorry I haven't posted in awhile here, but I'd do anything to see our girl Arle in Smash, she needs to complete the SEGA trinity! (Her, Sonic, and Joker)
Also bonus points if Sig gets anything in the form of Spirits or an Assist Trophy (I know he's very popular so that idea doesn't sound too farfetched), I just love the little guy so much!
Aside from that, I see Satan as a stage boss and either Schezo (casting spells and slashing with his sword), Rulue (essentially Knuckle Joe, but with WAY more kicking rather than punching), or Lagnus (Schezo but with light attacks) as Puyo Puyo's AT character.