User blog comment:Stevethebarbarian/Question/@comment-24277243-20151211155100

In most of Mothra's appearances, he/she's always had to team up with an outside force/gain an upgrade in order to beat the monster of the movie. That and people often view moths as fragile creatures, especially when one is up against a giant, radioactive monster.

Bagan's single appearance in Super Godzilla leaves quite an impression in my opinion. The aliens build him up as their greatest creation, a creature with Godzilla and Ghidorah's cells that were added to an already, supposedly, powerful monster. Bagan is so durable that atomic blasts from Godzilla do next to no damage to him. He's easily the most powerful kaiju in the game, who requires an upgrade in order to defeat (once Godzilla turns into Super Godzilla, the fight is actually pretty easy). But the problem comes from the fact that Toho hasn't given him a movie to demonstrate how powerful he could be. For all we know Bagan's supposed strength could just be a result of the game's programming, which encourages you to wait the fight out until you can turn into Super Godzilla. Those are my thoughts, at least.