Spider-Phoenix
#ChespinGang
For Dawn/Piplup, I think I really started to dislike them when Dawn got Cyndaquil and Piplup acted like a brat for no reason but being obsessed with being Dawn’s number one pokemon. And this against a newly hatched Cyndaquil. Piplup was always annoying but this made me kinda loathe him. Dawn disappointed me too because she didn’t hold Piplup accountable for his obvious flaws
I think it was more of a sibling-esque rivalry thing than anything with the oldest feeling jealous of the youngest getting all attention. If I recall it didn't take long for Piplup to get over it.