Hardest Post-Game NPC?

[meowmachine]

Who is the strongest post-game NPC?


Assuming all they have their highest possible leveled Pokemon and including Elite 4 rematches.

I would say Cynthia in Black 2/White 2 Hard Mode.

 

[Fluke]

I think there's already a thread like this.

Nonetheless, Dome Ace Tucker (Emerald) made me smash my GBA when his Swampert held onto its Focus Band four times in a row. He was definitely a pain in the butt.