>>56182684Depending how you view it; either Magma/Aqua, Flare, or Yell.
Magma/Aqua really started the whole "my plan is end the world" kind of thing that Pokemon doesn't really need. Plus, they feel so disjointed, living in caves and just kinda showing up, that their plan feels way more like a desperate play for attention.
If you think "end of the world" plots are fine with proper gravitas, then Flare probably is where it jumped shark. Flare's plot is just "Fashion, Fashion, Fashion, DEATH LASER, Fashion, Fashion!" It's just completely incoherent during a playthrough.
Yell is just when they gave up and made a "were bad cuz were bad, beat us to advance the story."