ive completed every mission except for this one, i need some tips

https://preview.redd.it/eg670x2lsuge1.png?width=999&format=png&auto=webp&s=81fd9e2fb5ac5578a9a23dd36b52ab37c1b16426

i know how to gravity cancel, but i am so bad at it. everytime i do hit someone, it does like 20 damage; every match i get like 50 damage added. is there any easier way to do this? like are there any legends or anything that would be easier to do it with?