I think either a Hisuian Typhlosion or a Fuecoco! Not only they're fire-types, but Briar likes Pokémon that look very animalistic like those two lol Not sure if she would catch them but at least I can say those two are Fire-types she really really likes (:

Personally I won't give her any more Pokémon because I think her team is perfect as it is right now, but maybe she could get Pokemas-like alts with those two Pokémon in the future :3c

Surprisingly enough, and even if Briar researches Legendary Pokémon, she wouldn't catch one. Not because she doesn't think she could, but because she only enjoys researching them and unveiling their secrets, not so much the battling part LMAO