Big Stone- Murk Forest

What are you supposed to do there?

I believe Eevee evolves into Leafeon if levelled up near there.

Not the mossy one, I mean the giant one in the middle of that one area.

Keldeo is summoned there if you bring the three Swords of Justice.

Ah. Where do you find Cobalion?

Midna Garden, you need to Heart Swap and then Waterfall.

Thank you.