Originally Posted by SoulStealer

Are you using fast forward? since if you are they often seem to attack a dead pest especially if all the pests are dead but the ability that kills them hasn't finished it's animation.

Rarely, but some girls have slightly longer special attack animations, so it even shows during normal speed. Star Lily is the one I regularly notice. Cactace is also very close to "overlapping" the animation for the next knight with her special attack, especially if the next knight is a short animation magic user like Violetta Tulip or DiYu dealing a "normal" attack.

Atk % up - just stack a bunch of girls who boost attack. Not especially clever but it works very well and most people have the girls to put together a team like this.

Def % up, counterattack (thorns) abilities - for use with girls like Anemone. Stack enough def so you can take hits all day and return damage every time.

Solar blast damage up - because of the way it stacks (each one is multiplicative, so two 20% up girls gives you a multiplier of 1.2 x 1.2 = 1.44), can be very effective with a high enough multiplier. I would not put any shine crystal % girls in there, since you want every slot to have a solar blast dmg up and the shine crystal girls work just fine in other teams. Similarly I think Leucocoryne's ability works across squads as well so it's not necessary to have her in the same one.

Shine crystal % up - more of a supporting squad, this one will generate tons of crystals to power your solar blasts. I would put it on a more defensive team so they spend longer in each fight and produce more crystals.

Skill % up - girls who boost skill proc chance, combined with strong skills. Atk % up is really helpful as a secondary. Although the third turn girls like Tachibana technically fall under this, I would actually consider using other girls instead because under most conditions it takes too long to activate. This somewhat overlaps with the next two types as well:

First turn victory - girls who boost attack/skill rate on the first turn, combined with strong AoE skills. The idea is to win the battle right away so the lack of boost doesn't matter for the later turns. If you're lucky enough to have Dendrobium/Cymbidium (I am not) this is pretty incredible.

Third turn victory - the crappier version of the first turn squad, girls who have a boost that activates on the third turn. You have to survive two turns of pounding with minimal boosts so a defensive team works better, and usually the only pests that survive until the third turn are stage bosses and raid bosses so strong single target skills will do well here. I like this one combined with life draining skills - once it kicks in you suddenly become very hard to kill and can drag the fight on for several more turns, even regaining life you lost in the first two turns and dealing tons of damage to the boss. If you're using this to hit raid bosses (not sure why you're nuking them, but maybe you're preparing a squad for the raid boss events later on) then the raid boss specific skills are useful too.

Speed squad - for the lazy farmers like me. Your squad needs to be strong enough to clear the map on its own. Stack speed up abilities so it'll reach the end of the stage before the other squads have too many encounters, saving you a lot of time fighting through the other nodes.

There's also situational girls that don't necessarily have special synergy but offer useful abilities depending on the map... Toad Lily, Edelweiss, Lavender and the like can be put in to keep certain squads alive, Lilac if you need one squad to ignore webs/tornadoes, Chocolate Cosmos can be put in on a side team to provide extra healing or Strawberry Candle if for some reason you don't have Chocolate or need more solar blasts, etc.

About the Skill activation girls for those that missed it.

Girls with Turn 3 skill ups stack by adding the two together 1.2 + 1.2 = 2.4x chance
Girls with chance based on affection stack by multiplying 1.2 x 1.2 = 1.4x chance (probably 1.44 but it only shows 1.4)

So placing 3rd turn girls together is a good plan but affection based ones not as much. Having said that, I have 2 of each and star lilly (+15% atk on 3rd turn) in the same squad and they dominate. Most of the girls with these skills seem to also have high Defence so they take very little damage.