Flounder

Flounder is Ariel's best friend. He is not very brave and often gets easily scared, but whenever Ariel is in distress, he would rise up his spirits to help her out in any type of situations.

Kingdom Hearts
''Ariel's trusted friend. Flounder will do anything for her. He's small and not exactly brave, but he'll never leave Ariel's side, even when it means facing danger.''

He appeared in "The Little Mermaid" (1989).

Kingdom Hearts: Chain of Memories
A young fish.

He's not exactly brave, but Flounder is Ariel's most loyal friend.

Ursula kidnapped Flounder as part of her plan to trick Ariel and steal the trident.

Kingdom Hearts II
The Little Mermaid (1989)

''Ariel's trusted friend Flounder would do anything for her. He's small and not exactly brave, but he'll never leave Ariel's side, even when it means facing danger.''

Kingdom Hearts
When Sora, Donald and Goofy first arrive, he was chased by Heartless with Ariel and Sebastian, but were saved by the trio. Because Sora and the others were new to the sea world, they did not know how to swim flexibly. Flounder, then became their instructor and had them chase after him so he could teach them.

When Ariel and the others set off to find the Keyhole, Flounder was the one who told them about the dolphin that would help them swim against the water currents.

Kingdom Hearts: Chain of Memories
Flounder appears as a fragment of Sora's memories. In this story, he was sent to the surface by Ursula so she could use him to make Ariel steal the Trident from her father. Towards the battle, Ariel was supposed to choose between giving the Trident to Ursula and losing Flounder. Ariel willingly gave up the Trident so that Flounder would not lose his life - but Sora defeated Ursula in the end.

Kingdom Hearts II
When Sora, Donald and Goofy revisited them, Ariel was under deep depression. Flounder wanted to cheer her up, and so he showed them a statue that resembled Prince Eric and asked them to move it to Ariel's cave.

When Ariel was turned into a human by sea witch Ursula, he and the others stayed near the princess to assist her.

Talents
Flounder does not seem to possess any certain skills as he not only gets trapped by Ursula but is also very off key when singing especially in Swim This Way. But Flounder does know what Ariel likes and knows his way around the ocean and is one of the most competent swimming instructors for Sora.

Trivia

 * Flounder along with Sebastian were originally there when Ursula turned Ariel into a human.