Board Thread:Questions and Answers/@comment-58.162.48.151-20150805054534/@comment-26513604-20150805155150

You can evolve regardless of level.

The evolved card gets a higher level cap of 10levels from the unevolved state, so if you maxed both units before combining, the effort in maxing the second card to full level is kinda wasted since you need less effort to max the evolved card than two of its uneveolved forms.