Wano Act 4 will break this website.
I crave the chaos of seeing so many Nakama join.
I believe Vivi is the first one to come, though. Vivi's goals are very similar to Vegapunk and Dragon's, and since Dragon and the Revolutionaries are big in this arc, it really is the perfect time to bring her back.
People can talk about power-scaling all they want, but Oda really doesn't care. If he wants a character to join the crew, he'll give them the power ups they need.
People act like Carrot is weak, when Brook and Chopper got low-diffed by Perospero, and Sulong Carrot was capable of doing serious damage to him. We thought Bepo was weak because he couldn't go into Sulong when he needed to, so, what does Oda do? Sulong steroid, which fixes Carrot's weakness, as well.
Momo went from being unable to do anything useful to carrying an entire mini-island to keep it from crashing and exploding in a single night.
Oda cares more about emotion than power levels and stuff like that. Half of the arguments here ignore that Oda himself doesn't really give a damn if the character is weak or not, he cares whether or not they fit into his narrative.
Momo went from getting beaten up by Kanjuro to being able to blow through Green Bull's giant wood form in a week. Oda has no problem giving characters like Vivi, Tama, and Usopp power ups (remember Usopp's Dials?) to even their strength.
Weak characters can still join the crew, it will just piss people off because they'll have to gain crazy power ups to catch up.