@OrangeKirbyGuy I put Tank in that tier because its high Attack skills are quite good, but it has to use MP for EVERYTHING. I put Flower there because of its good healing, but lack of (powerful) offence.
Pop Star is in the D tier because it only focuses on team support, and one of its most powerful moves (Way Out Of Tune) has the potential to possibly KO a teammate, if used with Assists.
While it is mainly used for support, I'd say the Pop Star is insanely OP. It can end Quarrels instantly, it can put all the Miis relationships at a high level, it can distract enemies, it can make other Miis go a second time, AND it can revive Miis!