I agree that temporal buffs could be hard to implement, or rather, balance out well. I mean, you could restrict it to, for example, one buff/debuff at a time, but even then it would have to be further restricted (like decreasing its actual buff with rising level, like mentioned somewhere above) and then would become pointless at some point. But I agree that the Café would make a great and logical place to put a spectator lobby. There could also be a system similar to SSB4's spectator mode that gives you the option to bet some money on one of the teams. All in all, I feel like Inkopolis Plaza as a whole still has a lot of space for new ideas, either for actual new game mechanics or just little gimmicks to kill some time.