I already told earlier that no 4th gen Pokes yet in Liquid Crystal
Hoenn starters are available as well Mewtwo. Check out Cerulean Cave for it. No TM-list and Wild List yet for the latest version
Mewtwo is not available. Mudkip on the other hand, is.
He's not available by fishing in route 44 anymore (but if you have an old enough version, you would still require Super Rod for it). You get Mudkip on the second Orange Island.