Actually I spent a little time looking through and here's what I think;
If you dig through Fennekin's learnset on the basis that Glow Punch was renamed or something, the only move that is remotely punchy is Power-up-Punch. So what I think after looking at their animations and stuff is that
Glow Punch is in fact Power-Up-Punch.
If you look at around 0:49 on this video (it's really blurry) of Power-up-punch and this one of the so called 'glow punch'from about 0:16 you can see that the animations are basically the same.
Additionally, Fennekin learns Power-Up-Punch and it is super effective on Litleo, which is an normal-fire type (Apparently there was a super effective sound when the move hit on Litleo).