Google Play services not supported by device

[AC Question]

A little help is needed here please. I recently installed the Thunder_Strike custom rom on my Gionee Pioneer P2. Now I get an error message "Google Play services, which some of your applications rely on, is not supported by your device..." when I run the GMail app or Hangouts (hangouts doesn't even run properly at all). This wasn't so before I installed the custom rom. What can I do please?