Best of cactus is they can’t move much so you can pull mean tricks on them. We have put a pair of skates on one and have launched him against a wall... well, against a lot of walls, but we’re not sooooo wicked. We’ve left space to let him pass through.
It’s up to you to position his branches the right way in order to overcome each and every wall faster and faster.
BONUS: When you finally decide to let him crash against a wall, once you’re at it, finish him till he has got no branches left.