And thus was summoned the 'mon that should not be...

Ia! Ia! Missingno f'thagn!

You still don't get it, do you Delphox?
Chesnaught is Grass/Fighting, whose type combination triumphs over Greninja.
By forcibly transmuting the two, you have created a physical manifestation of 「contradiction」 itself.

The Litwicks have stopped smiling.