The Kaiju are frequently reoccurring threats in many games on Puppy Paws. Though in the original game the males above (https://inkbunny.net/submissionview.php?id=1184421) were the villains and the females below (https://inkbunny.net/submissionview.php?id=1184386) were the heroes. The males are still a lot more aggressive than the females in the games and both seem hellbent on destroying buildings and vehicles and of course eating people. They are massive in size ranging from several stories to the size of skyscrapers. They aren't a breed of creature, they are individuals, so if one is killed there wont be more the same as them. However this means of course that each one is notoriously difficult to kill and they are often bosses or threats you can only shoo away or capture rather than kill outright.
The Kaiju Hunters (https://inkbunny.net/submissionview.php?id=1184461) AKA the Heroic Fairies are heroes set on vanquishing the Kaiju or simply preventing them from being a threat to people. The Kaiju Hunters also appear in other games as heroes where the Kaiju aren't present as well. The Kaiju Hunters might by small compared to the Kaiju but their super strength and special abilities means they are often the only ones capable of handling the task.