Usually I'd agree with Waffles on most votes, but on a character vote like this I have other preferred options. As much as I'd like to go with Jacinto due it being the best mechanically:
[X] Erika Furuwada: Pale face set in a scowl. Dark blue eyes with her long blue hair styled into pigtails. A worried looking Carbink trailing after her. Her white and pink cardigan, pink skirt and black leggings seem to be stained by an unknown drink. Your attempt at saying hello was met with an irritated snarl.
[X] Nemona Mendoza: She walks in already wearing the school uniform just like you. She had brown skin, black hair with a singular green streak, and orange eyes that immediately locked on to you and Roland. A Chimchar was clinging onto her back. Before you could greet her, the words had already left her grinning mouth.
Erika has a chance to be a good tutor, even if it doesn't work out, we keep our concerned older sister shtick and also get some possibly interesting character interactions to test the QM's writing chops. Then, Nemona, I mean, c'mon. It's Nemona, we'll get lots of EXP. Does it help anything really or advance the plot? Not really, but we do get to see Nemona in this Universe and grind Battle stats.