I know I am not contributing much but holy jesus is this thing's awesome! I don't know what it is, but having a grass type with only to weaknesses (If I'm not mistaken), annoyer moves, lots of power and flexibility makes it such a good pokemon...and don't forget the butt flower!
I have only one move I always use, the other ones are changed ->Synthesis.
Synthesis is there for several reasons, the most important being:
->You can't be toxed as a bulky mon, weather isn't always there, so healing 50% is possible
->No leftovers makes this move even more awesome.
People might suggest that Leech Seed&Giga Drain > Synthesis, but I swear without I always regret it not using synthesis.
It can be "always" used except switching into poison and flying types.
Also finally, by god the SD Set. Wreaks everything and survives everything. The only thing it lacks is good couverage with its moves:
SD Synthesis EQ Power Whip (Talonflame, Skarmory, Dragonite :( ) Because I often get to +4, but it still doesn't help against those...if it would learn at least poison jab T_T