Website Pokémon Amino explains: “Any Raichu would act as a rival towards it’s pre evolution form, Pikachu, and Raichu in the anime mostly appear to be [a] smug Pokémon, that enjoy seeing their pre evolution form struggle.”
While the animation is goofy-looking, the Pokémon Sun Moon anime continues to get more and more interesting for longtime fans.
But the biggest rivalry of them has been with Raichu.