Lookin' good. Izayoi and Carol should handle Brock easily, two 'mons for each, even easier if Izayoi evolves firsthand. Oh, and be careful: CAlice evolves at level sixteen, not twenty-six. Not that it matters, none of Brock's girls (?) should survive long enough to throw rocks at her, and you don't even need to grind that high to be safe against him. She seems to be headed to the Alice->EAlice/LAlice/BAlice (hah) route, too, which means she'll be slightly harder to keep alive but will also destroy everything in her path if you do. Oh, and unless my memory fails me LittleLegion is just a Normal-type, high-ish powered attack move with no secondary effects. Nice to have, but not what you want to be using with an Alice.

Mystia is surprisingly effective for an early bird, but yeah, her standard evolution doesn't cut it in the late game. AMystia is a great, fast special tank (Moon Stone though, not Sun) and has fantastic type coverage via TMs. LMystia hits really hard and fast both physically and specially, and is also Dark/Flying, but needs a Sun Stone and is kinda fragile for a L form. And then there's GMystia, which is just weird (Flying/Steel, evolves via Thunderstone, good attack and sp. def. but horrid HP and defense and low speed for a bird, and a very varied and promising learnset with, for example, a very early Tailwind).

Chen's simple, she (he!) just hits hard and fast. Can learn Dig and Earthquake and use them with STAB, which is great, but her overall stats are a bit poor. There's also AChen, which is basically the same but with more TM compatibility, a different learnset (earlier Poison Claw and natural Earthquake at L40!) and 50 more base points to improve her HP and (slightly) her defenses with. Not sure if it's worth the Sun Stone. Same goes for Sunny, really, which doesn't even have alternate evolutions. Fire types are nice in any case, and there's not much else to realistically choose from in that department: Mokou and Utsuho are rare-ish (look out for the latter after Nugget Bridge, though,) Kisume is a different kind of 'mon altogether and Rin comes a bit too late, IIRC.