I think it has a lot to do with the state of the game too. Take a 200k absorb or heal and a player with 400k health. Putting up 200k absorb so the enemy has to burst 600k+ while you're in CC is a lot better than them only having to burst 400k while you sit in CC waiting to use a 200k heal. It's the same way Druid healers are stronger when the game is slower.
Has anyone noticed this? Pet battles get tons of small incremental changes, hotfixing abilities, bugs, and adding more content and functionality. PvP would be pretty amazing right now if it received anywhere near the same level of attention.
If something is too overpowered in pvp, they should just put in a small hotfix with a small change to adjust it, rather than these massive sweeping nerfs and buffs that almost always go too far and take far too long to implement.
Because Pet Battles does not affect PvE in any way.