Ash could use his Pokémon. Pikachu, for example, could use its electric attacks to short - circuit any devices or barriers holding Ash captive. His other Pokémon like Charizard could also help by using their strength or special abilities to break free.
Well, he could be used as a bargaining chip. Team Flare might try to exchange Ash for some powerful Pokémon or valuable items. They could also try to force Ash to reveal any secrets he has about powerful Pokémon or rare items he's come across during his travels.
Another plot twist could be that Team Flare's leader has a change of heart after kidnapping Ash. He realizes that Ash's pure love for Pokemon is something that could be used for good. So, instead of harming Ash, he decides to team up with Ash to fight against a common enemy that threatens both their interests and the Pokemon world as a whole.
Well, Team Flare might see Ash as a threat to their plans. By kidnapping him, they could prevent him from interfering in their evil schemes. They might keep him locked up in some secret base. Ash, being the determined trainer he is, would probably try to escape and find a way to defeat Team Flare from the inside. He could befriend some of the captive Pokemon in the base and use their help to break free.
Another thing that could occur is that Ash's friends would be very suspicious. They might think Ash has gone to the dark side. So they could try to rescue him. This would lead to a lot of drama and action. There could be epic battles between Ash's friends and Team Flare while Ash is caught in the middle, trying to figure out what to do and where his loyalties truly lie.
His Pokémon might be confused at first. They are used to Ash being on the side of good. But if Ash believes he can change Team Flare for the better, his Pokémon might go along with it. However, they could also sense the danger and be on high alert. For instance, Pikachu's electric attacks might be more charged up than usual, ready to protect Ash at any moment.
A new villainous trainer group. They might see Ash as a threat to their plans of dominating the Pokémon world, so they kidnap him to stop him from competing in important battles or tournaments.
There's also a possibility that it's a misanthropic Pokémon that just doesn't like humans interfering in the Pokémon world. It sees Ash as a symbol of human intrusion and decides to kidnap him with the help of the eevee to send a message to all human trainers.
Well, perhaps Pikachu would go on a heroic quest to rescue Ash. It might team up with other Pokémon like Charizard. They could follow the kidnappers' trail, facing various challenges along the way, like battling wild Pokémon or getting through difficult terrains.
One possible plot could be that Ash is kidnapped by a rival trainer group who want to steal his Pokémon. His friends then have to embark on a rescue mission, facing various challenges and battles along the way.