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Yeah.. you also need to many HMs to get through caves like Mt. Coronet. Going back and getting Pokemon for Defog, Rock Climb, AND Waterfall is really a pain.
Umm.. You should be fine with those Pokemon as long as you have type advantage. If you don't have a Ground-type attack, then it will be kind of hard, though.
The only thing that you should really worry about is the Nasty Plot / Baton Pass with Ambipom, but I don't think it will have time to...
Turtwig, because it has type advantage against the first few gym leaders. So basically, I only used it for speeding through the game to get to training/breeding REAL Pokemon. :P