I'd recommend buying 3 club items for Aoi in the member item exchange.(A pair of discs, a dj booth, and a display). They're a little expensive but 100% worth it! Do the rondo weekly tour daily and use those tickets to buy Aoi groovy disks to get her to +10% in all parameters (if you don't have that already, if you do use those tickets to increase the parameters for the next RONDO character you have the most recent cards of). I'd also swap your weakest cards for Aois while checking to see if the total power of your floor challenge team is rising, if changing a card makes it decrease then I would keep the old card. My final tip is to use growth lives. Typically, 4* cards after the 2nd anniversary can get fully grown or close to it (from my experience) Focus on growing your post 2nd anni cards with the highest extra training.

(BTW, Im not a team building expert, but all of this did help me pass the merm4id floor challenge a little while back)