OK, IMO, which assist you go with depends on how you want to treat your assists. Light and medium shadows are good at neutral. You can get some mixups (cross under with medium, high/low with light), and can mostly protect her since Fukua comes out a bit behind. Heavy shadow is similar, but it's hitbox is way worse than the other two. It's better if you use it in a rushdown setup against already grounded opponents. Drill is a pure pressure move. You can do some cute things by firing projectiles behind drill and getting a lot of chip or just running in behind it, but I find Bomber to be much better for this.