Board Thread:Question and Answer/@comment-173.32.216.135-20150616063246/@comment-7620285-20150616124429

check if they are part of an elemental team (might see a symbol of an element and number) or locked, or even part of your normal teams.. if they are both part of any type of team you can't evolve them but if one is freed up you can choose the one that's on a team to evolve and then select the free one.