Captain Olimar is a tiny astronaut from the tiny planet Hocotate. Olimar, like the rest of his kind, is only the height of a quarter (his proportions are strongly inflated in the Smash games). Oilmar orders and commands the Pikmin through his games.
Captain Olimar's first appearance was in the Nintendo GameCube game, Pikmin, where he is the main and only playable character. His first adventure tells that his ship, the Dolphin, crash lands on a Distant Planet, where he's aided by the Pikmin, an indigenous plant-like alien race to find and repair his ship; as oxygen, which is plentiful in the atmosphere, is lethal to him, he has only thirty days to completely fix his ship. There are three possible endings to this game; in the canon ending, Olimar returns home with his ship fully repaired, segueing directly into the beginning of the next game.
More on Olimar's character is elaborated in Pikmin 2; in the game, Olimar is identified as the top employee of Hocotate Freight Company. Additionally, he has a wife and children, and communicates with them whenever he can through the course of Pikmin 2.
Olimar is joined by Louie in the second game. During the events of Pikmin, Louie was on a delivery and was entrusted with a load of golden Pikpik carrots. On his way, however, he got hungry and ate the whole load, claiming a "ravenous space bunny" ate them. Louie then returned to Hocotate and falsified his report to the President, forcing Hocotate Freight into bankruptcy. In the beginning of Pikmin 2, Olimar returned from the Distant Planet only to find that the company was 10,100 pokos (the universe's currency) in debt; upon his return, the company was forced to sell the Dolphin after he had spent days repairing it. The shock of the revelation of the company's fate causes Olimar to drop a bottle cap that he brought home for his son. However, an old, used Hocotate Freight Ship, analyses it, and discovers that the piece is worth 100 pokos; when the President learns about how there's more objects on the Distant Planet, he makes Olimar and Louie return there in the Hocotate Freight Ship to gather treasure to pay off the debt. After obtaining 10,000 pokos of treasure, Olimar accidentally leaves the Distant Planet without Louie, forcing Olimar to team up with the President to save him.
Olimar is based on Mario, as he has a similar nose, and his name, prior to translation from Japanese to English "Orimā", is "Mario" backwards in Japanese when written in kana. Likewise, the lankier Louie, whose Japanese name is "Rūi" is derived from Luigi (Ruīji) in both name and body proportion.
In Super Smash Bros. Melee
Captain Olimar makes only one minor appearance in Super Smash Bros. Melee:
As a trophy
Captain Olimar debuted at the same time as Melee. This trophy is one of the most unique in the game in the way the player obtains it. In order to get the Captain Olimar trophy, one needs to have a save file of Pikmin on their GameCube memory card, making it one of the rarest trophies in the game. Melee will automatically give the player the Pikmin trophy the next time he/she starts it up.
However this can be bypassed by using software such as Action Replay.
The main character of the game Pikmin, Captain Olimar crash-lands on a mysterious planet after his spaceship malfunctions. In order to get off the planet, he must gather the pieces of his broken ship, but the atmosphere of the planet is poisonous to Olimar. As a result, he has to enlist the help of the native Pikmin.
There is also a trophy of 100 Pikmin, which is obtained through the lottery.
In Super Smash Bros. Brawl
As a playable character
Captain Olimar is featured along with the Pikmin as a single playable character entity. Olimar is very weak on his own and needs to summon Pikmin to his side with his special Pikmin Pluck move in order to use stronger attacks with them, and he needs at least one to use most of his attacks.
Due to his great damage racking capabilities, very good camping game, and being quite unpredictable due to the different types of Pikmin, Olimar is ranked 3rd on the tier list.
A veteran spacefarer in the employ of Hocotate Freight. After crash-landing on an enigmatic planet, Olimar met the mysterious beings known as Pikmin. He enlisted their aid to find his spaceship parts and help him escape. Once home, he found his employer on the verge of bankruptcy. He was sent back to the Pikmin world with his partner, Louie, to repay the company debt.
In Super Smash Bros. 4
Olimar returns as a playable character in Super Smash Bros. 4. He was given a whistle on the bottom of his helmet (similarly to what the 3 main characters have in Pikmin 3), and his spacesuit is now lighter. The two top buttons on Olimar's suit are now blue instead of red. There is a Hocotate Freight patch on both of his arms now. Olimar was the first veteran to be confirmed after those revealed at E3 2013. Four of his palette swaps switch him into the protagonist of Pikmin 3, Alph.
Super Smash Bros. for Nintendo 3DS trophy descriptions