If we accept that, in X-Men 3: The Last Stand just prior to being killed,
Professor X transferred his consciousness into the body of his comatose twin
doesn't this imply that he no longer has his powers? Even if
his twin is genetically identical,
there's no guarantee that they would have manifested the exact same powers.
Similarly, I don't recall Professor X actually using his powers in X-Men: Days of Future Past, does this mean that he has lost his powers?
If he does still have them, is there a canon reason explaining why they returned?