Pokémon Black & White
Emile obtained HM02 Fly from Bianca, but found that Roc was incapable of learning Fly (as an Archen). Emile then looked through the Pokémon in his PC and found that the only one with wings, Celebi, was also unable to learn Fly. With no choice, Emile looked up Pokémon capable of learning Fly near him, went onto Route 6, and caught the first Tranquill he found—a Level 23 male—in a Quick Ball. Emile taught him Fly and decided to give him a nickname, so he flew to Nimbasa City and, with the help of the Name Rater, christened him Necessity. He used him to fly back to Nuvema Town to collect TM17 from Professor Juniper, and then back to Driftveil City. He deposited him in the PC offscreen.
Offscreen, Emile withdrew Necessity in place of Lillipap. After obtaining HM03 from Alder and using it to teach Surf to Ottawa, Emile had Necessity fly him to Driftveil and then Striaton. In the midst of his exploration of Wellspring Cave, Emile deposited Necessity back in the PC to withdraw his first Blitzle to use as a Flash HM slave.
Necessity is sent out against Virizion, and he is the last Pokémon on the field as Virizion is captured.
- Fly (Pokémon Black & White - Episode 29: Charge N Up–Present)
Emile caught Tranquill solely out of the necessity of catching a Pokémon that could learn Fly. Though he also mentioned that Necessity was a cute name for a bird.
- Emile often spoke of wanting to like the Pidove line. Sadly, he feels the line has a lot of wasted potential in that its stats don't match up with its movepool, due to the fact that it mostly learns special attacking moves by level up when its stat spread reflects that of a physical attacker.
- Emile only uses Necessity when he has to fly between locations, especially with how much backtracking he'd have to do without Fly. Due to a Power difference between Fly and Acrobatics he prefers the latter as Roc's Flying-type move (especially the added Power when not holding an item).
- Normally Fly is a 95 Power move and Acrobatics only 55, but the latter is a one-turn move that doubles in power when the user is not holding an item and Fly is a two-turn move).