Pokémon Brilliant Diamond and Shining Pearl feature 493 Pokémon, and while most evolve simply through leveling up, a few have specific requirements before they can evolve. Some Pokémon require learning a particular move first, and one of those is Aipom which evolves into Ambipom.
To get Ambipom in Pokémon Brilliant Diamond and Shining Pearl, you will need to teach Aipom the move double hit and level it up. If Aipom levels up while knowing this move, it will evolve into Ambipom and only if it knows Double Hit. Aipom learns double hit at level 32 in Pokémon Brilliant Diamond and Shining Pearl.
Aipom and Ambipom are normal-type Pokémon. Aipom can be found by slathering honey on honey trees—though the rate is somewhat low. If you get an Ambipom with the Technician ability, it can do some serious damage with multi-hit moves.
Ambipom can be a solid Pokémon if you teach it the proper moves. Some fantastic moves for Ambipom are egg moves which means you will need to breed it to maximize its move set.
For more information on Pokémon, check out Pokémon Go Mischief Unbound: Event Details, Spotlight Hours, and Raid Hours and How to check IVs in Pokémon Brilliant Diamond and Shining Pearl on Pro Game Guides.