Recovery set: ON
Fastest stagger and fastest hold.
Thumbs up for Master for bringing it up.
Works on human players as well and tested. PKH has to be used for human players (No-timing needed). 2x P into ground hit only works against the CPU in Scramble, reason for that is because the CPU techs up/wake up kicks in a different manner. Don't use P, P, 3P. Use P, PKH, 3P instead. The falling debris of objects creates an entirely different forced get up and stun. (Similar to Bass's 214P on a BT opponent in vanilla).
Note: Scramble/Crimson, Zack Island/Fireworks coconuts, and Lorelei pumpkins have different falling speeds. Situational to a degree and varying for different characters on all situational needs. Different characters also have different ground attacks with different recovery for notice.
Note 2: Depending on timing, there are cases where invulnerability will still commence from a forced get up opponent. You may have to try different attacks/slower launchers that are within late start up or frame advantage to land.
Other good bits: Jann Lee's wall T on Scramble near the boxes can take heavy advantage of this.