About the title, if they don't want to use "Age of Apocalypse" because transformers and Avengers are already using the "Age of " for their films.
How about "X-Men: The Apocalypse"? Its simple yet striking.
WOLVERINE X CYCLOPS X STORM X ROGUE X ICEMAN X PROFESSOR X
X-MEN - FANTASTIC FOUR
R I 5 3
MISTER FANTASTIC 4 INVISIBLE WOMAN 4 THE THING 4 HUMAN TORCH