Battra Rescues Mothra

As Godzilla prepares to kill Mothra by toppling the Cosmo Clock 21 ferris wheel on top of her, her former arch-rival Battra manages to heal from his injuries just in time to save her, catching the wheel with his legs. To say Godzilla's pissed off by this development is quite the understatement. Though Battra previously saw humanity as the one enemy to Earth's continued existence, he's realised that Godzilla is the bigger threat, and thus has teamed up with Mothra to subdue the rampaging King of the Monsters.

Example of:
Big Damn Heroes