Wigglerman
Smash Ace
This discussion about Kazuya is sort of pointless and slightly amusing imo.
He will never be fully tapped nor is there any reason to invest the time and energy that's needed to do so.
Never fully tapped? Sure, it's unlikely. But no reason for anyone not to invest in him? I wouldn't go that far. If anything I'd love more people to try to push him to see how far he CAN go. If he's got so much potential to unlock I'd like to see him someday at the highest peak he can be. And if someone did get to that point I doubt their investment would be 'wasted'.