I assume you mean other than Torchic (Fire Bird), Treeko (Leaf Lizard), and Mudkip (Water Pokemon). The fact is, you can't.
trade
no you can catch a charizard in pokemon ruby you can get it as a kanto starter
Mudkip is available as a starter pokemon in more than one games. They are Pokemon Ruby, Pokemon Sapphire, Pokemon Emerald, Pokemon Omega Ruby and Pokemon Alpha Sapphire.
mudkip
Torchic, Mudkip, and Treecko.
trade
you can't.
wait you mean ruby is sinnnooohhh
Pokemon Emerald,Ruby and Sapphire
Ruby, Sapphire and Emerald.
torchic,treecko and mudkip
Train your starter and other of the strongest Pokemon you have often.