>>27864852According to statistics, that was the most overwhelmingly common Starter Combo used in X/Y. I recall seeing that as many as 47% of all the people who played it ended up with the Greninja/Charizard combo in their first run, if they had many, which is especially staggering when you consider that there are nearly a dozen combos you could make.
It makes sense considering Greninja is the new Charizard.