Everyone bring your nature power users for this one. Super effective, double damage on top of that, and can never miss? Plus it's a TM that we get at the second gym.
Other than that, haven't checked the obtainable list yet but VOLCARONAAAAAAAAAAAAAAAAAAAAAAA!
Edit: Having now had a look at the list, we have Squirtle, Totodile, Turtwig, and Fenniken all becoming in game events, while Mudkip loses its status as one.
Also, Volcarona, Mandibuzz, Hippowdon, Drillbur becoming an event? Pack your bags boys we're going to the desert.
Also also I found the fact that Axew is now obtainable (implying rock climb), but Feebas still isn't very interesting.