Top anime theme songs I can imagine the bands covering:

Roselia: Magia from Madoka Magica
Afterglow: The Day from My Hero Academia
Pastel Palettes: Clear from the new Cardcaptor Sakura

I’m a bit less certain for the other two, but I feel like either Kasumi or Kokoro would unironically sign the Sword Art Online theme, lol. Anyway, that brings us to...

Top meme songs for the bands:

Poppin’ Party: All Star
Roselia—We Are Number One (Ako literally just tells Yukina the title without explaining anything else. The results are hilarious, though I unironically want to see Yukina rock Bring Me to Life, too.) Pastel Palettes: The world’s softest Rickroll.
HaroHapi: Disaster Transport (This is a less popular song, but with lines like “look out for space pirates, we’re heading to Alaska,” this is made for Kokoro.
Afterglow: Ran just screams like that cowboy in the AAAHHH video. That’s it.