UPNetwork -> Anime -> Kanto -> Island of the Giant Pokémon
#17 "Island of the Giant Pokémon"
Ash and his friends land awkwardly on an island. Pikachu is not with them, and Ash realises that half his Pokéballs are missing! Team Rocket, landed elsewhere on the island, find their own Pokémon missing, including Meowth. Meanwhile, Pikachu has found the Pokéballs of Ash's other Pokémon and opens them, pulling Charmander, Bulbasaur and Squirtle together. They go looking for Ash, although Bulbasaur thinks he has abandoned him. The others try not to think of it, since they have been abandoned before.
Pikachu-tachi meet up with Ekans and Koffing. Meowth orders the two to attack Pikachu, but they refuse, because he's not their master and they are only bad if their masters are being bad. The two sides group up (Meowth a little reluctantly, heh) to find their masters, while their masters are looking for them (well, Jessie and James are being bad trainers and are doing no such thing -_-;).
But, there are more difficulties than that. Giant Pokémon are on the island, which chase the Pokémon and scare them. In escaping, they finally meet their masters, who are also escaping. To cut a long story short, in the way they escape, they succeed in beating the giant Pokémon. Problem? This island was a Pokémon theme park, the giant Pokémon just mechanical tourist attractions... the park is owned by Giovanni, who is NOT thrilled....