This team is looking alright so far, but Chimecho's stats are actually pretty bad imo. I mean, check its data and you'll see what I mean. If you want a better Psychic, try getting an Alakazam, which you can catch and evolve from Abra. To evolve into Alakazam it does require trading so if you can't trade then I guess you can't get one.
Also, for a more defensive Psychic, you can try Bronzong, or even catch yourself a Ralts on the route east of Hearthome City and eventually evolve it into a Gardevoir or Gallade, which have pretty good movepools (Gallade especially, since he learns a lot of attacks) plus there's also Espeon, which you can evolve from the Eevee you get from Bebe by maxing out its happiness at daytime. Remember, Eevee can be obtained as you as you reach Hearthome unlike in Diamond and Pearl.
So yeah, quite a few options for Psychic-types in the game.
Also, Toxitoad is not really called that. It's Toxicroak.