>>4950856490% is clearly an exaggeration, but I can assure you this shit is a problem
I'm assuming you are not in the postgame yet, so try to catch Alpha Lucario and Garchomp, and then every single legendary. Like without even attacking them once, just take an Ultra Ball and toss that shit at full health. No status, no attacks, no nothing
I noticed this against Cresselia and it basically ruined the rest of the game, because it's borderline impossible to damage Cresselia without it not healing instantly
