No dont get rid of Hyperloli
Chibi Ninja is one of the best girls, both her voice/quotes/ and the banana slip are adorable

Ofc feel free to shuffle her away (though I "obviously" disagree haha), but personally I think she is pretty strong, her ulty deals bunch of damage comparable to non event gacha girls. plus she gets it to lvl 5 and 4 item slots so she is pretty solid.

Well I ran a 4-1 ratio for a time and it was nice and all, but they tend to struggle a bit more at level Bosses, especially the tougher ones, that soak lot of damage.
3-2 ratio for AOE - Single Target attack, seems to be the best.
If its AOE from a 6* usually one is more then enough, if it comes to 5* you usually need 2 of those to get rid of the normal enemies. And since you cant guarantee it will proc having the 3rd AOE girl in the party is insurance of a sort (granted its still up to RnG but thats why we try to mitigate as much of it as possible), while leaving 2 strong single target nukers to clean up whatsever left.

Now if you have someone like Dendrobium with at least 2 more Skillblooms invested into her, she tends to wipe the small enemies by herself, but again depends on the mobs themselves, eventually stronger enemies will be introduced in later missions, so at least 2 AOE girls are the bare minimum I would use.

From testing though the 4-1 raito is for the current mission good enough if you are lazy and want to get the grind done as soon as possible without minimum effort. Take longer with level bosses though
3-2 ratio can take on tougher enemies but can take a round or two longer on normal enemies, but finish Bosses faster. Thats where that 4.0+ damage really shines (Alpinia, Mei, Keria, etc).
So its pretty much the same in the end.

Also in DMM version, Mei got boosted up to 5.1 damage or so ! (According to Wiki), rendering her the most powerful single target nuker in the game, without any bonuses applied.