UFO

David's Magnezone (Japanese: サトシのジバコイル Deividdo's Jibacoil), nicknamed UFO, was captured an unknown amount of time before Best Wishes!, and was traded to David for his Rotom after both realized their unruly Pokemon actually listened to the other trainer, in Best Wishes!.

History
UFO started off with Eve having a very cocky personality, feeling bigger and better than most Pokemon but it begins to mellow out after its trade to David, making friends with the group's Pokemon and forming a tight bond with David.

UFO's Magnet Pull ability created a running gag that John's belt would be attracted to UFO and he'd slam into the Pokemon, causing the surprised Magnezone to react with a ThunderShock. The ability also has its uses as it brings key items to the group when needed.

With Eve
Eve had UFO for an unknown amount of time before the fateful trade, although it is known that UFO was very disobedient to Eve, opting to slack off instead of listen to her when she knew that UFO was capable of so much more.

While helping Pokeathlon newcomer David out, Eve lended UFO to David and he lended his Rotom, Vroom Doom, to her, because both needed a Pokemon for the opposite thing (Power for David, Stamina for Eve). David and UFO got along great, same with Vroom Doom and Eve, which was odd because both Pokemon were said to have been disobedient.

The two decided it would be for the best to trade Pokemon. The trainers agreed to it, and they swapped Pokemon.

With David
Since the trade, UFO seems to have become a happier Pokemon. Its cocky pesonality eventually mellos out and it becomes good friends with the rest of the Pokemon in the group. Magnezone's Magnet Pull ability offers some good comic relief dragging John into its body, surprising UFO, causing the Magnezone to zap John. Magnet Pull also came to have some good in it as well, however.

Following his journies through Sinnoh, David dropped off UFO and the rest of his Pokemon at his house, starting with a clean slate for his travels through Unova.