Suisei strikes me as the kind to prefer cutesy/elegant pokemon, as well as psychic and fairy types, but for the sake of diversity, I'm not gonna be paying attention to them as much. Most of her team isn't meant for battling, and are instead kept around as companions/pets, but a couple of them pack a punch for when she needs them. ALSO I PROMISE I'LL PUT IMAGES/GIFS/SPRITES/WHAT HAVE YOU here eventually, toyhouse is just REALLY not liking me right now v___v
Primarina, Lunatone, Misdreavus, Ledian, Stufful, Pansage
Primarina is pretty obvious, but Suisei gives me huge diva vibes [even if she's about as nice and as sweet as can be], and so it's her star pokemon and main fighter, and she's probably had it since she was younger. I feel like it would have the same temperament as her superhero sona, but it never switches out of this unlike her. It's dramatic. It just will not shut up. Also, I think it'd be kind of cute for her to have a half water-type instead of a full-on fairy-type as her star, mostly because her love for spa trips. Whenever she can't go out for one, Primarina can make a nice bath for her instead.
Lunatone is probably one Suisei also gets a lot on games like these, but hear me out. She had a really hard time picking between Solrock and Lunatone [and even then i think she would have a solrock stored somewhere], but its her second to Primarina, and also... the aesthetic. It's believed to have come from space and to have a link to the moon phases, so I think she would find that especially interesting.
At some point she caught a Misdreavus [probably fairly recently?] and regretted it. She thinks it's cute, and it's sweet when it wants to be, but it likes to startle her by screaming. It's like a toddler begging for attention. She loves it, but she is so tired. She wants to evolve it at some point to curb its mischief [which... won't really work], but she hasn't been able to get her hands on a dusk stone yet.
Ledian is often associated with superheroes from what I've seen, so of course I had to give her one u_u Like her Primarina, it's brave and melodramatic, but... not as strong. It usually gets its ass kicked. Instead of fighting, it's usually meant to throw up moves that boost the rest of her team, such as Safeguard and Reflect. Also, it uses starlight as energy, which she likes for the aesthetic, similar to Lunatone.
Stufful is a pokemon that Suisei has always wanted. It's small, it's cute, and she couldn't help but nab one the moment she saw it. It's used as a companion, something to pet and cuddle with while she's relaxing. She's debating on evolving it, but it's a constant back and forth, because on one hand she wants it to be big and strong, but on the other... It's gonna be awfully difficult trying to cuddle a Bewear at night.
Pansage is probably out there, but tying into Primarina's whole spa thing, the leaf on it's head is used to relieve stress. Like Stufful, it's one of those pokemon she doesn't really use for battling, but rather as a pet. It's definitely a lap monkey. Also, it collects berries for her, which she always appreciates. When it evolves, however, it's gonna become... a lot more quick-tempered, and the leaf is going to become bitter. Again, same situation as Stufful, she doesn't know if she actually wants to evolve it or not.