One day Stoutland found Litten weak and decided to be its guardian figure, they began living together in an abandoned house. However, Stoutland was getting too old to find food so Litten was doing the hunting for it. Stoutland later teached the Fire Cat Pokémon how to put more power into its Ember attack. Then Stoutland saw that Litten had returned with Ash, who explained what happened. However, the Alolan Persian attempted to attack it but Ash protected it and Litten was able to scare Persian away for good. After that Ash had returned to the house to discover that Stoutland and Litten had moved to a new house.
Stoutland seemed to get weaker as days passed while the tree started to lose its leaves, and it was seen coughing while Litten was doing its training, but it still managed to demonstrate Litten its Fire Fang. Later, when Ash reached the bridge with his Pokémon after Litten asked for his help, it actually fainted and Ash decided to carry it to the Pokémon Center, but Nurse Joy told him that she couldn't cure Stoutland. Then Litten, who was still worried about Stoutland, took it back home. After Litten tried to train itself to use Fire Fang but failed, it slept with Litten but this time it passed away during the night. In Litten's dream, Stoutland was leaving Litten further and further until it completely disappeared. In the morning, when Litten woke up, Stoutland's body was gone, with the implication that it had passed away. In the end, Litten saw its soul among the clouds after Litten itself noticed the rainbow in the sky.
The elder Stoutland is mentioned by Ash when he reminded about it upon seeing a young and healthy Stoutland prior Pokémon School’s Treasure Hunt task began, and wishes to let the elder Stoutland know that Litten is now under his care just fine on its behalf.
It was later confirmed that it had disappeared because it passed away a few days ago at time when Litten joined Ash's crew. His spirit resides at Poni Island, where the other dead spirits of Sofu, Mallow's mother, and Kiawe's grandfather reside as well. There, he finally met Litten once again, and was glad to see him evolved into a Torracat, as well as successfully learning Fire Fang. Stoutland then helps him learn Fire Blast. After Hapu becomes an official Kahuna of Poni Island, the fog began to lift and Stoutland bids its friend a farewell and departs to afterlife.