Isn't there a tag for this, where to two do this kind of butt kick?
Not yet. As of right now posts featuring it are just tagged with Stand By Me (original source of the scene) and Lycoris Recoil (where a parody popularized it in anime circles). Not sure if there's a name for it yet elsewhere unless we did something like stand_by_me_kick, but that seems kinda awkward
EDIT: I took a look and there is indeed a KnowYourMeme page for it, which uses the title Chisato and Takina Kicking Each Other's Butt. It's long but it's not like we don't have other long tag names for memes based on their KnowYourMeme titles.