User blog comment:Dark Knight 178/Stop giving Genders to Pokemon. It is very Annoying./@comment-6632076-20150518203423/@comment-8182065-20150519012130

It can be assumed Charizard, Lucario, and Greninja are male mainly because they have a high chance of being male when bred, 87.5% chance to be exact.

However, I would only go as far to refer to Lucario as a male, because of the voice actor.