If you don't have Feeva, you could try using Zerafalga. Feeva functions like no other there really isn't any substitute for her except Zelnite who pales a bit in comparison. I probably ought to make another guide as this one was possibly too specific. For Diana - Kikuri, Luka, or Narza should work.
There probably is no sub yet for Colt, so if you can't use him maybe use Kanon, Tridon or Eve. Another good Lead/Friend combo would be Kanon/Rosetta or Zerafalga. Basically HP+ Lead/BC+ Friend. You could also probably use a Diana friend.