In The Mystery is History, Oliver owned a Lanturn, which he often uses to swim underwater. It would also play with a baby Lugia nicknamed Silver, which it befriended. It reappeared in A Parent Trapped! and A Promise is a Promise.
In Just Add Water, Dorian used a Lanturn during his battle against Ash. It went up against Totodile and won with a Spark-Take Down combination.
In Lapras of Luxury, Naomi's Lanturn used its Supersonic waves to help her locate of a group of Lapras by their singing voices.
In Pruning a Passel of Pals!, Kyle's Lanturn competed in the Wallace Cup. It went up against Ash's Buizel in a battle and easily defeated it.
In The Legend of Thunder!, a Lanturn was swimming in a lake.
In Enlighten Up!, multiple Lanturn were living in Lake Slowpoke.
In Pokémon Heroes: Latios & Latias, a Trainer's Lanturn competed in the Tour de Alto Mare.
Multiple Lanturn appeared in Destiny Deoxys.
In Pokémon Ranger and the Temple of the Sea, multiple Lanturn were present during the final showdown with The Phantom and his crew. They briefly reappeared in a montage in The Rise of Darkrai, which chronicled the preceding nine movies.
Multiple Lanturn appeared in Kalos, Where Dreams and Adventures Begin!.
A Lanturn appeared in a fantasy in Clemont's Got a Secret!.
In Going for the Gold!, multiple Lanturn were living in the Ambrette Aquarium.
In Securing the Future!, a Lanturn joined the rest of Alola in showering Necrozma with light so it could return to its normal form.
A Lanturn appeared in Pikachu's Exciting Adventure!.
||Lanturn, the Light Pokémon. The light that emits from its tentacle-like limb shines bright enough to illuminate the bottom of a deep sea.
||Lanturn, the Light Pokémon, and the evolved form of Chinchou. Lanturn's antenna light is strong enough to penetrate the ocean, and can be seen on the water's surface.
Lanturn is based on an anglerfish, more specifically the footballfish, although it shares some similarities with dolphins. It is also possible that Lanturn's origin contains a small piece of Apollo, the Greek god of light whose signature animal was the dolphin.
Lanturn is a corruption of lantern. It may also be a combination of lantern and turn (as in "turn on the light").
Lantern is literally lantern.