My Grandfather VS Your Father is the 31st episode of Season 17.
Romeo's grandfather, Doctor Undergear and Night Ninja's father, Chaos Khan, get into a fight after diffusing their grandson and son. But when their fighting gets worse, Catboy's crazy magic decides to put their battle to an end.
The episode begins at night in the park where Romeo with his robot and Night Ninja along with his Ninjalinos are having an argument with each other while the four PJ Masks were shooting annoyed looks at their enemies arguing. They've seen this already before Captain Jake became an official member of the PJ Masks.
Eventually, Romeo, and Night Ninja give up and agree that they are too evenly matched one on one on one. Romeo tells Night Ninja that his grandfather, Doctor Undergear, could beat his (Night Ninja's) dad, Chaos Khan, in a fight. Night Ninja replies to Romeo saying that his dad could beat his grandfather in a fight. But before they could agree to get their grandfather and father and use them to help them fight each other, Catboy gets too irritated and uses his super cat speed to run up to Romeo and Night Ninja to tell them that using Doctor Undergear and Chaos Khan to fight each other is a bad idea. Then behind them, Owlette, Gekko, and Fish Boy approached with looks of agreement.
But it was already too late! Romeo, his robot, Night Ninja and his Ninjalinos ran off in different directions to get their grandfather and father to help them. As they left, the PJ Masks all let out heavy sighs together.
At Gear Island, Romeo starts telling Doctor Undergear about all of the things Night Ninja and his Ninjalinos did to him and meanwhile at the Chaos Fort, Night Ninja tells Chaos Khan about everything Romeo, and his robot did to him.
- Some of the episode's scenes are similar to the ones from My Dad VS Your Dad from Dexter's Labratory, Apartnership from Fairly Odd Parents, and Just Dancing from Star Darlings.