Seraphims vs Chibi strawhats
I am still 100% sure that is why Bonney is back too.
No way its a coincidence we got aged down Seraph Warlords and basically the first thing Oda does is bring back Bonney.
Then again, I can't think of what she will do. Unless there is some trick to the Seraphs, like, they lose power when aged up. Just as example!
Worst case, somehow the WG used her power to turn them into kids.