Fun fact: Because of the abnormal amount of hitstun on Luna's grounded dash attack and Flying Frog, this is all guaranteed. The Souper Anti Air -> Aerial can be subslituted for a Souper AABB, it does the same amount of damage but I've found it to be more difficult to get consistently.
How it's done: Luna approaches with her grounded dash attack, then executes a turn around jab into Flying Frog. She murtag drops the flying frog into a grab out of shield, which the then souper cancels into an anti air attack to send the opponent into knockdown. She ends the combo by using her aerial to pop the opponent back up. The inputs for the combo would go something like this, Tap Direction+A, Tilt Direction+A, A+B, R (hold through next input), X+Y+A, Y, Tilt Direction+A.
This is done by pressing and holding B for Luna's special, and then shield cancelling by pressing R. Luna will do her signature laugh without actually throwing any bats. Do this repeatedly to frustrate opponents.
This isn't specific to Luna, all characters can do it, but hers is easy to demonstrate with. By pressing B immediately before landing, Luna can cancel her landing lag into her special. This also allows Luna to use her special even while her Slam meter is fully charged. You'll know it worked because the cloud of dust that normally appears around Luna's feet when she lands won't be present. I know this also works with Robin Hood, so I would guess all characters can do it, but I have yet to fully explore it.