You make a really good point, Caliann: The opposition to Miguel’s ultimate goal — becoming a musician — is his family, in the land of the living, Abuelita, Miguel’s grandmother, and in the land of the dead, Mamá Imelda, Miguel’s great-great-grandmother. It’s not until de la Cruz’s treachery is revealed at the end of Act Two that the opposition function shifts to the real Nemesis in the story: Ernesto. In turn, Abuelita and Imelda turn from enemy into ally, thus, donning Trickster masks.
Indeed, since Ernesto appears to be Miguel’s great-great grandfather for a portion of the story, it’s fair to think of him wearing a Trickster mask for that period of time.
We can even go further: Hector is a Trickster who reveals himself to be a Mentor — the true songwriter and creative spirit who knows his way around the land of the dead. Even Mama Coco wears a Trickster mask, her silence (Enemy), her awakening and revelation of the truth at then end (Ally), settling into her role as Attractor.
I think it’s interesting that we can view so many of the Coco characters through the Trickster lens because the Trickster is a hugely popular character in native cultures in the Americas, so yet another way the movie embraces the spirit of Mexico in its storytelling.