I think we just have to accept that the anime and the games have different sets of rules. But the trips snivy defeating Pikachu is something i don't think i will ever come to accept. On to the gym leaders, there position is to test the abilities of the trainers and gauge if they are deserving of the badge. In a serious battle the gym leaders would wipe the floor with trainers otherwise anyone could just up a gym. The PWT at least in the games is a probably a good guess at how powerful most of them are.
Oh and the games came first.
"over the laws of light, over the moon by midnight"