Melvin was a magician who had a lot of bad luck: his assistant quit on him, nobody liked his show and he got fired.
His luck changed when he caught a bunch of Exeggutor, thanks to Ash and his Pokémon. But Team Rocket intervened and nearly stole his Exeggutor, but his Exeggcute evolved to save him. Unfortunately, since all the Exeggutor used Hypnosis on Team Rocket and each other, the Exeggutor were out of control.
Ash's Charmander tried to stop them but it was no use. Misty gave Melvin the courage he needed to perform his "Raging Fire" trick and woke up all the Exeggutor at once. His own Exeggutor was happy to be with its trainer again, and he soon parted ways with Ash and co.
This Exeggutor is Melvin's partner Pokémon. As an Exeggcute, Melvin could juggle it, which didn't impress the crowd much. It used Hypnosis to control Ash and ordered him to do what Melvin wanted. When it saw Melvin was in trouble, the six eggs came together and evolved into an Exeggutor, which used Hypnosis. Unfortunately, it was unintentionally controlled by the other Exeggutor who had the same idea and started a rampage in town. When Melvin and Ash's Charmander snapped all the Exeggutor out of their trance, this one returned to Melvin, who was happy to see it again. Known moves: Hypnosis.
These Exeggutor were caught by Melvin in an attempt to make people watch his magic show. When Team Rocket intervened, they all used Hypnosis on each other and formed a mob, running rampant around town, unaware of what they were doing. Thanks to Melvin and Ash's Charmander, they woke up and returned to the Leaf Forest.