Question: what app do i use to make gacha videos?
Answer: CuteCut Pro (This app does cost money but I have a tutorial on how to get it for free. ... 
Kinemaster (Though I don't have this app, a lot of GachaTubers use this app to make their Gacha Videos. ... 
VLLO (This app is like CuteCut Pro, so if you cannot get CuteCut Pro, you can get VLLO and it also has Copyrighted free music.