Major appearances
Misty's Goldeen first appeared in Pokémon Emergency!. It wasn't seen very much throughout the series due to it being a water-bound species, flailing when displaced from it.
Other
In Here Comes the Squirtle Squad, a Squirtle knocked Pikachu into a lake, which angered a Goldeen living in it. It proceeded to attack Pikachu with a Horn Attack, which severely injured it.
In The Great Eight Fate!, a Goldeen was part of Juan's Sootopolis City Water Exhibit. It and Juan's other Pokémon were captured by Team Rocket, but they all worked together to escape. Goldeen reappeared in a flashback in the next episode.
In Historical Mystery Tour!, multiple Goldeen were in a stall run by Team Rocket.
In JN024, Goh caught a Goldeen while fishing at Resort Area. In JN031, it helped train Nami's Feebas for the Water-type Pokémon Friendship Contest.
Minor appearances
A Goldeen appeared in The Water Flowers of Cerulean City, under the ownership of Lily.
A Goldeen appeared in a fantasy in the banned episode EP035.
The Sensational Sisters own multiple Goldeen, which first appeared in The Misty Mermaid. They reappeared in Cerulean Blues and in a fantasy in Alola, Alola!.
In Showdown at the Po-ké Corral, multiple Goldeen were living at Professor Oak's Laboratory.
In Pikachu's Vacation, a Goldeen was at the Pokémon Theme Park.
A Goldeen appeared in Misty's fantasy in Bye Bye Psyduck.
A wild Goldeen appeared in Pikachu's Rescue Adventure.
A Goldeen appeared in a fantasy in The Totodile Duel.
In Beauty and the Breeder, a Pokémon Breeder's Goldeen participated in a Pokémon breeding competition.
In The Joy of Water Pokémon, a Goldeen was receiving special treatment in a salt bath tank in the Pokémon Center located near Lake Lucid. Another Goldeen was being personally treated by Nurse Joy due to health problems.
In Around the Whirlpool, a Goldeen was stolen from the Pokémon Center of Blue Point Isle.
In Bulbasaur... the Ambassador!, multiple Goldeen were among the feuding Pokémon at Professor Oak's Laboratory.
In Enlighten Up!, a giant Goldeen was living in Lake Slowpoke.
In On Olden Pond, a Goldeen was living in the old lake.
A Goldeen appeared in Jessie's fantasy in Three Jynx and a Baby!.
A Coordinator's Goldeen appeared in May, We Harley Drew'd Ya!.
In Pokémon Ranger and the Temple of the Sea, The Marina Group used multiple Goldeen for their Marina Underwater Pokémon Show.
A Goldeen appeared in Drifloon On the Wind!.
Multiple Goldeen appeared in Giratina and the Sky Warrior.
In Up Close and Personable!, a Goldeen was living in the lake near the Pokémon Summer Academy.
In Strategy Begins at Home!, multiple Goldeen were living in a lake. Team Rocket spent a part of the episode trying to fish for one.
A Goldeen appeared in the opening sequence of Zoroark: Master of Illusions.
Multiple Goldeen appeared in Kalos, Where Dreams and Adventures Begin!.
In Going for the Gold!, multiple Goldeen were living in the Ambrette Aquarium.
Multiple Goldeen appeared in Diancie and the Cocoon of Destruction.
A Goldeen appeared in The Guardian's Challenge!.
A Goldeen appeared in a fantasy in Yo, Ho, Ho! Go, Popplio!.
A Goldeen appeared in I Choose You!.
Multiple wild Goldeen appeared in Alola, Kanto!, with one appearing in a photo taken by Rotom.
In Deceiving Appearances!, two Goldeen were silhouetted at Aether Paradise.
In Dewpider Ascending!, multiple Goldeen swam along the river.
A Goldeen appeared in Keeping Your Eyes on the Ball!.
Four Goldeen appeared in Pikachu's Exciting Adventure!.
Three Goldeen appeared in Legend? Go! Friends? Go!.
Multiple Goldeen appeared alongside Goh's in JN024.
When released from a Poké Ball, Goldeen will use Splash, having no effect on the battle.
When released from a Poké Ball, Goldeen will use Splash, having no effect on the battle.
Goldeen is also a Pokéfloat. It will appear from the bottom of the screen but quickly drop down to the bottom again, knocking out any character it hits.
Trophy information
These Water-types are often referred to as "water dancers," as their elegant fins make them incredible agile underwater. They can even travel upstream in rapids at a speed of five knots; of course, they're not quite as nimble on dry land. Goldeen's Horn Drill is so strong that it can KO an enemy with one strike if it connects.
Goldeen will sometimes be found in a Poké Ball and will use Splash when released. It does nothing to affect the battle. On the official blog, Masahiro Sakurai commented that Goldeen appearing at the most critical of times is in keeping with Murphy's Law.[1]
Trophy information
"A Goldfish Pokémon. In contrast to its elegant appearance, it has a wild temperament, and its attack with its horn is severe. Among the techniques it can master, Horn Drill is especially reliable. It evolves into Seaking, but if raised without evolving, it can learn the powerful Bug-type Megahorn. There are male and female Goldeen--the male's horn is longer."
Goldeen will sometimes appear from a Poké Ball or even a Master Ball. As in the previous games, it uses Splash when released, having no effect on the battle.
Trophy information
NA: This Water-type Pokémon sports a fancy horn on its head. An excellent swimmer, it can literally swim up waterfalls. In the world of Pokémon, this elegant Pokémon has a variety of effective moves in battle. In Smash Bros., however, all it can use is an ineffective Splash attack.
PAL: A Water-type Pokémon with a distinctive horn. Thanks to its powerful fins, Goldeen can swim comfortably through the most torrential waters and even up waterfalls. It's known for both its strength and grace. That said, don't expect it to make a big splash in this game - just a little one when it uses Splash... It's super ineffective!
Goldeen returns as a Poké Ball summon, retaining the same behavior as before.