Emma showed control of her powers and leadership skills. when Stryker returned and destroyed her school and captured her friends...she stayed at home. Remember, this m is Stryker, who had kidnapped her for years...but she cared so little that she stayed home. She also didnt care to help her friends in part 3 (then again, nether did Nightcrawler, which should have been explained)
Deadpool (probably) did NOTHING. Dont give me that "they didnt explain it so im guessing" argument. Deadpool never felt the need to ever address Stryker, Wolverine or Sabretooth again. That is established movie continuity. Mind wipes are you GUESS.
Gambit...again...did not care about Strykers return and almost genocide of all mutants years later, so he stayed to himself. Of course, you could explain reasonably that he had no way of knowing it was even happening.