Characters i believe that should be in this game are
Raiden (MGR) Final Smash: Activates Ripper mode
Solid Snake Final Smash: Combos a player
Jetstream Sam Final Smash: Uses Zandatsu
Blade Wolf Final Smash:Throws high frequency knives at players
Sauske Uchiha Final Smash: Activates Sussano
Scorpion Final Smash: Uses get over here chains
Shao-Khan Final Smash: Brings Hammer and smashes into player
Issac Clarke Final Smash: Uses plasma Cutter
Kratos Final Smash: Blade of Olympus Charge move
Predator Final Smash: Uses thermal sensors and slices opponents that fail to avoid him
Kirito Final Smash: Asuna appears and helps combo another player
But anyway that's what i think should be inserted to the game
post your ideas here and i will try to get these to the developers
Anyway Thanks.