>>30838504>>30840155>>30840461>I could've sworn his dex entry talked about wearing the disguise to more easily make friends, but all it says is it wears it to get close to people and pokemon."Closer" can be interpreted in more than one way, kind of like "keep your friends close and your enemies closer".
But I think that the totem Mimikyu was lonely and envied that it wasn't a pikachu because of all the love Pikachu was given, as seen by all the posters, merchandise, and even the children's drawings of Pikachu. It's also possible that totem Mimikyu was actually a dead Pikachu and the blonde girl in the photos was its previous owner, wanting you to get a glimpse at its memories before battling you.
Meanwhile, we have anime Mimikyu who despises Pikachu in a very refreshing way. Can't wait to figure out its motives and hope to god they don't try to make Mimikyu just a shitty tsundere for Pikachu.