>>27729814>>27729714Actually if you check the official website, it says that people in Alola speculate that Raichu changed in Alola due to eating too many sweets and pancakes.
However pancakes is a mistranslation of malasada, which is a type of doughnut eaten in Hawaii, which I believe Hau references in one of the early trailers.
Source;
http://www.pokemon-sunmoon.com/en-ca/pokemon/alolan-raichu/"Even Pokémon researchers don’t know why Raichu’s form changed in the Alola region. The people of Alola seem unconcerned by the question. Their guess: maybe it ate too many sweet and fluffy round pancakes!"