In the episode in which Ash's Pikachu faces off against Blaine's Rhydon,after rhydon took a hit from thunderbolt with virtually no effect Ash says 'Pikachu,the horn!' pikachu then hits the rhydon's horn which instantly KOs it. This shouldn't happen because ryhdon is part ground and as such immune to any and all electric attacks. There is an episode where pikachu's thunderbolt is redirected to a rhydons horn due to the lightning rod ability which does nothing to the rhydon,as it should.