Soooo as with a majority of the canons in this game, I don't know the first thing about MLP. However, not knowing the first thing about MLP does not make it any less obvious that Pinkie Pie is basically the most precious thing ever.
I think she brings a light-hearted element to the game without being basically the corniest thing ever. She's there, she's happy, she's Pinkie Pie. But she's also got her own demons and I think it's super interesting to see her in this place that is basically the antithesis of all things her.