Kirby - It happens every game

Considering the games are about a cute, tiny ball of pink that goes on massive genocidal rampages while devouring everyone and everything in his path, consuming their very souls to gain their powers, this is rather fitting.

It is like Gurren Lagann

Start: Two brother set our on adventure.

Final boss: Driving a robot inside a robot inside a robot inside a robot to defeat what can be considered god in a galaxy-scale battle

End: Happy wedding in a small outdoor chapel.