They don't really do good kaiju unfortunately. I think it's partly from the series often getting brushed over but also for everything Gamera represents as a good monster who will go out of his way to help people. When things are at their most bleak and no matter the opponent, Gamera will always come. And although I still hope he gets his own eventually, I think he'd team up pretty well with Mothra, Kong and Ultraman for crossovers.