I figured that I should just mention this here as well, Entei learns Sacred Fire.
Battle Vid evidence: GG2G-WWWW-WWWX-PQ2F
Also a few more tests regarding Mat Block to answer some questions a while back.
Mat Block vs Feint:
Absol uses Feint
Greninja uses Mat Block
party's side did not take any damage from the opponent Furfrou Headbutts.
Mat Block vs Phantom Force:
Turn 1
Gourgeist hides
Absol switches to Greninja
Turn 2
Greninja uses Mat Block
Gourgeist hits Greninja
a message stating that Gougreist broke through Greninja's protection was also stated.
Conclusion: Feint does not lift the effect of Mat Block. Naturally, because it hits before you use Mat Block. Phantom Force and thus Shadow Force DO lift the effect of Mat Block, but likely only if it hits after Greninja uses it. You can't remove something that isn't there after all.
Also tested a thing with Protean. Unsurprisingly, if you Trick-or-Treat a Protean Pokemon, and they attack causing a switch in their type, they will lose the added Ghost-type.