Ace Combat 5 and MLP:FiM actually have a lot of similarities in terms of mythology. Here's the legend of the Razgriz compared to the show:
Whenever history witnesses a great change (creation of the world by Celestia and Luna), Razgriz reveals itself...first, as a dark demon (Nightmare Moon). As a demon, it uses its power to rain death upon the land, and then it dies (Celestia imprisons Nightmare Moon in the moon). However, after a period of slumber, Razgriz returns, this time, as a great hero (The Elements of Harmony).
Also, the game's story arc is similar to the show. After saving the world from a trerrible fate, the heroes seem to fade away unrecognized (In the show, the Nightmare Moon conflict is never mentioned after the first two episodes).