TPDP: Shard of Dreams -Extended-: 10 ??? Damage
Definitely the most annoying fight in the game so far. Damage leads with a Speed Renko (Light), who has the unique ability Stargazer that makes any weather summoned by it last permanently, and she uses that along with a Black Choker to set up an almost-guaranteed Duststorm. And of course, two of Damage's puppets, Power Marisa (Light/Dark) and Speed Konngara (Steel/Fire) can perfectly take advantage of that with their Sand Devil ability to double their Speed.
The rest of his puppets aren't slouches themselves, especially the dreaded Power Aya (Wind/Fighting). The last two are Extra Parsee (Nether/Warped) and Power Maribel (Illusion). The latter takes advantage of Duststorm as well, as her Boundary Blurrer ability doubles every stat except for Speed while a weather effect is active, though luckily thanks to the AI being stupid she never got to take advantage of that.