Climb up a tall mountain where you are on the same level as the clouds. The hard part is you have to find a way to push it off mountain ... that's why Dragonite is rare. People have to shove it off a mountain before it evolves.
How does skarmony evolve? (I know he does.. the game just hasn't learned it yet)
You have to take it to a place called "Acme University" and get it to earn its Bachelor's Degree in Evology. Then it will be granted with the Keys to Evolution - a one time deal to evolve into a Phanpy.
What do I do to evolve my Suicune?! HELP! I've tried EVERYTHING!
That's really easy! First you take it to Charzard Valley where it needs to learn Ember, then you go to Burned Tower so it can learn about its tragic past and then you go to ruins of Alph where it gets granted a wish from the Unowns so it can evolve into a caterpie. Then you just have to hope it really does wish to evolve!