1. Torchic. Why? There's a Water/Grass pokemon in the wild on Route 102
that pretty much ruins the starter's usefulness when trained. That
pokemon's name is Lotad, which has 3 evolutions just like the starters, only that in order to get to the third evolution in the Lotad family, you need to use a Water Stone.
2. Lotad(like I said on the first question), Geodude in Granite Cave's basement, Makuita(to outnumber Normal-types quicker until you evolve Torchic into Blaziken), Poochyena(for advantage against Psychic-types),
Doduo(once you evolved your Torchic into Blaziken), Rayquaza (once you get to the Sky Pillar, why? He makes beating the E4 easier in Emerald, if you have enough money for revives and hyper potions/fullrestores, of course)...
3. I also suggest you check the R/S/E FAQs and ask for game help in the General R/S/E FAQ sticky that's located in that same subforum before even thinking about making a new thread asking such questions...