i made a new wind for fb and put her on my team and battled down to cirrus where i burst by the time i got there my new wind was lvl 3 and i burst her with just shield smash til she got the rest of her skills,as for low lvl teams assist bursting its good if it your own team that way you assist one for a couple days so it lvls alot then switch to the next one and just keep alternating which fire assist bursts that way they all lvl up alot faster