Explosives
One of the most important factors will be explosives. Bombs, drone bombs, spider bombs, explosives in general are going to be important. These are going to be what deals heavy damage to the enemy, and you can stack a bunch of them up on the the stage, and push them towards the enemy. Explosives will only damage the opponent, they won't damage who they came from, but pushing your opponent's bombs back towards them will still get rid of them.