Well see here's my reasoning for this: You're right, it has a good speed already. But if they give it Chlorophyll, they won't have to raise it's speed stat to a ridiculous level in its Mega form. And it's dependent on Drought (*cough*Groudon*cough*) or Sunny Day, both of which have a limited number of turns they are in affect.
I do think we can safely rule out that, like Blaziken, it's hidden ability would become its mega evolution's ability. Absolutely no point to Unburden when he needs to hold a mega stone.[/quote]
I'd rather see it get something like Leaf Guard.
That last part, though, is certainly true.