Whether or not you already know, Pikachu the Pachirisu is alive.
Evidence: (In the story)
●I thought since Pikachu's death that it didn't actually die, because Vanilla didn't check whether it was breathing or not. And she confirmed (indirectly) that Pikachu didn't die by, if you guys remember, one, important thing someone said: "a Pachirisu who's fur color was changing."
●Shelly had told Vanilla that Pachirisu's fur color would change for some time, so... the 'someone' might have met the Pachirisu when its fur color was changing back.
●Also, when Vanilla went to Pachirisu's/Pikachu's grave, she noticed a shadow (though it could've been a Mimikyu) near the grave.
●If you guys think about it being buried, well... We never really saw Pikachu the Pachirisu's moveset. Thus, it could know the move used for digging, dig.