Flamme Rouge tries to train Ninjaminus to become Assistant to the Mysterious Mountain Guardian as she needs help against Ninjaka who again threatens her refuge. Thanks to Gluglu, Flamme Rouge realizes that Ninjaminus is not only useful in its form of Gigantus.
The following characters appeared in the episode "A Teeny Weeny Problem":
The episode begins outside the museum where Connor, Amaya, and Greg are just leaving after finishing a tour. Greg takes a look at the souvenir coin that Amaya got during the tour, but he accidentally drops it under one of the plants. Fortunately, Greg has a magnet on hand and fishes the coin out from under the plant pot. However, he notices Teeny Weeny’s tiny footprints leading out into the streets. That night, PJ Robot shows the PJ Masks from the PJ Picture Player that the footprints are leading up to the Mystery Mountain portal. Fearing that Night Ninja must be using the Transforming Splat to turn Teeny Weeny into the Splat Monster again, the team heads over to Mystery Mountain to stop him from doing so.
The PJ Masks arrive at the pagoda, but they are too late: Teeny Weeny becomes the Splat Monster again. An Yu shows up, though, and reveals that she was the one who brought Teeny Weeny to the mountain. The reason why is because of his act of kindness in the previous episode. She wishes to repay him by teaching him how to control his Splat Monster abilities so that he can become the Mystery Mountain Guardian’s assistant, as according to one of the ancient scrolls: “one day, the mountain will be saved by a loyal follower - a mighty one.” That being said, the group heads outside.
During the training process, Teeny Weeny is given three courses testing his agility, precision, and balance. An Yu demonstrates what to do in each course, and Teeny Weeny attempts to follow along on her level. However, the results are not what she expected. He keeps stumbling on the obstacles, ends up aiming his shots at himself instead of the targets, and loses his balance on the poles. Finally, An Yu enlists the PJ Masks to help out in the final exercise. She has the team attempt to face her off first, then attempt to face off Teeny Weeny. Teeny Weeny tries to attack them, but he falls down, get sent up in the air by a spring trap, and lands violently.
Frustrated with his failures, Teeny Weeny turns back to normal and begins to head down the mountain. Gekko comforts him, telling him that he does not have to be a Mystery Mountain Guardian assistant if he does not want to, but An Yu disagrees, knowing that the mountain will be in great danger if he does not comply with his destiny.
Halfway down, An Yu asks Teeny Weeny to turn into the Splat Monster again and move one of the huge boulders to block the pathway to test his strength. Teeny Weeny turns into his monster form again, but he refuses move the stone. Instead, he angrily turns into a big ball of splat. In response to his attitude, Gekko reminds An Yu that she had been in this situation before when she was trapped in the Dragon Gong. She thinks about it, and she agrees: she was forced to obey anyone who possessed her staff, and she hated it.
Suddenly, Night Ninja and his Ninjalinos appear and sticky splat the PJ Masks and An Yu onto Teeny Weeny. They overheard and oversaw what was going on and decide to teach them how they control the Splat Monster. The Ninjalinos push the group down the mountain, and the kids are sent back into town. Teeny Weeny is forced out of the splat, and the splat gets stuck tightly in the portal, preventing the kids from re-entering the mountain. The PJ Masks try using their powers to unblock the portal, but without any success.
However, Teeny Weeny has a plan. Even though the Splat Monster cannot break the splat, he can use his mind skills to remove it. Meditating, he gently places his hand on the splat and concentrates on feeling the flow and being one with it. Soon enough, he merges with the splat, and he re-enters the mountain, becoming the Splat Monster again. Night Ninja and his Ninjalinos see the others come in and try to escape, but they grab them with their powers and send them into the portal and back into town.
An Yu thanks Teeny Weeny for his help in saving the mountain and acknowledges that he is a master of wisdom and more than just a follower. Bowing to each other, she encourages him to take his own path and control his own destiny and bids him farewell, anticipating that they will meet again someday. Teeny Weeny thanks her and says goodbye, and he leaves the mountain, sneezing and alternating between his Splat Monster form and his normal form. With that, the PJ Masks’ signature victory phrase is proclaimed, and the episode ends.