They could team up to rescue a kidnapped ninja. The cat could track the kidnapper's scent, and Naruto could engage in combat when they find the enemy. Naruto's determination combined with the cat's stealth would make them a formidable duo in this rescue mission.
The cat could have the ability to turn invisible. This would be really useful in spying on enemies or sneaking into dangerous places. Naruto could use this to his advantage during missions.
They could go on adventures in the forest outside the village. For example, they might encounter strange creatures that the cat's instincts help them avoid or deal with.
They could go on a journey to explore hidden and dangerous lands in the Naruto world. Maybe they'd encounter powerful and mysterious ninja clans or ancient beasts. The dragon's abilities, like flying and breathing fire, could help Naruto in battles and in reaching inaccessible places.
They could explore ancient ruins. Maybe they find a hidden cave filled with rare Pokémon. Ash's battle skills and Lillie's knowledge of Pokémon lore would come in handy.
They could go on a journey to find a hidden vampire lair. Maybe they'd encounter other mythical creatures along the way and have to use their wits to outsmart them.
Well, they could embark on a journey to find other tailed beasts and try to form a new kind of bond among them. This would be an adventure full of challenges as some of the tailed beasts might be hostile at first. Naruto and Kyuubi, as brothers, would use their combined strength and Naruto's persuasion skills to make peace with them. Along the way, they would also learn more about each other's capabilities and grow closer as brothers.
They could go on an adventure to find a powerful treasure that combines the power of the One Piece and some kind of ninja - related artifact. Maybe they'd have to fight against a new enemy that is a combination of pirates and rogue ninjas. They might travel to new islands where Naruto's ninjutsu would be useful for exploring hidden caves, and Luffy's stretching ability would help them reach high places or cross large gaps.
One possible adventure could be them getting involved in a local Pokémon festival. They might participate in contests or help organize events. Ash could show off his battle skills in friendly exhibitions, while Lillie could share her knowledge about Pokémon care with the festival - goers.
They could have some really cool adventures. For example, they could team up to take on a powerful villain that is causing chaos in both their worlds. Naruto's ninja skills combined with Batman's detective skills and gadgets would make for an unbeatable team. They might also go on a journey to find a way to send Naruto back to his own world if that was the case, encountering all sorts of strange creatures and obstacles along the way.
They could go on a mission to save the village. Naruto's experience, Inojin's skills and Himawari's hidden potential could combine to defeat a powerful enemy threatening the Hidden Leaf. For example, they might face a rogue ninja who has a new and dangerous jutsu. Naruto would lead the way with his Rasengan, Inojin would use his art techniques to create distractions, and Himawari could use her Byakugan to spot the enemy's weak points.