Deku Scrub

Deku Scrubs, also known simply as Dekus are a tribe of small forest creatures that spit Deku Nuts at their enemies when threatened. They are plant-based creatures that have skin seemingly made of wood and hair and "clothing" made of leaves and flowers. They usually appear in a small flower-like tuft of foliage which they hide within when threatened. They often appear as enemies, but despite their antagonistic nature they tend to be friendly, at least when they believe it to be in their own benefit. They appear in Ocarina of Time, Majora's Mask, Oracle of Ages, Oracle of Seasons, and Four Swords Adventures.

Ocarina of Time
Deku Scrubs first appeared in Ocarina of Time, where they primarily appear as enemies Inside the Deku Tree where they are subordinate to Gohma. Here Link learns of his ability to deflect their nuts back at them with his Shield for the first time. Unlike other enemies, once struck they will not be destroyed, and will run around in a panic. When Link approaches, they will plea for mercy and offer him some advice to progress through the dungeon.

A group of three Deku Scrubs appear prior to Gohma's room, guarding the doorway. Unlike previous Deku Scrubs, these enemies will become stunned on the stop when hit, and will not give up unless Link defeats them in the correct order, a secret revealed by Deku Scrub defeated previously in the dungeon. This can be remembered using the phase "twenty-three is number one". When Link beats them, they reveal to Link the strategy to use in order to defeat Gohma.

In the Master Quest version of the game, the Deku Scrub that reveals the correct order is replaced by a Mad Scrub, and the order to defeat the three Deku Scrubs is changed to 3 1  2. Link can only discover this new order by trial and error.

Business Scrubs are Dekus that have taken to selling certain items, but they will only offer these items once Link defeats them. Business Scrubs appear within the Lost Woods but are also common in many caves and secret holes in the rest of Hyrule. While most of their deals are extortionate, some of them will offer important items such as a Heart Piece or even the ability to carry more Deku Sticks or Deku Nuts.

Mad Scrubs appear in the Sacred Forest Meadow when Link is young, and also in Kokiri Forest as an adult. Unlike regular Dekus, these are far more aggressive and will attack in bursts, and will make no attempt to bargain with Link and can be destroyed in battle.

Regular Deku Scrubs also appear in the Lost Woods, most notably in the Forest Stage. Here, a group of Deku Scrubs will judge the "face" of any vistor who stands on the stage, and reward them depending on what they think of it. This reward varies from Rupees, nothing at all or a hail of Deku Nuts. If Link visits with the correct mask, he will meet a large Deku Scrub who will offer him a greater reward. According to him, the Skull Mask looks like the Deku's sacred forest totem.

One normal Deku Scrub also appears in the Lost Woods making his home in the top of a tree from which hangs a small drum-like target. If Link hits the center of the target three times in a row, he will be granted a larger Bullet Bag.

Majora's Mask
Majora's Mask explores a different side of this species, in which there is a functioning society composed entirely of Deku Scrubs, known as the Deku Tribe. They are situated in the swamp of Termina under monarchial rule. The Deku royal family is composed of a King and a Princess, who are served by guards, yes-men, and a butler whose son had died mysteriously prior to the game. The Deku of the swamp are also hinted to have a sophisticated education system. However, if an unknown stranger ever goes near a Deku, it will attack; walking close to them forces their passive bodies into their Deku Flowers. Dekus normally live in either a nest or a Deku Flower, and if other Dekus try to enter without permission, they usually become enraged. Some Deku have propellers on their heads which allow for flight.

Skull Kid also turns Link to a Deku Scrub at the beginning of the game. When Link was healed, he received the Deku Mask. Link in his Deku form was able to perform spinning attacks, shoot Bubbles, perform a Deku Flower Jump and glide using spinning flowers, hop across water and have the ability to retreat into a hardened nut-like shell for defensive purposes, but it is unclear if other Dekus share these abilities.

Mad Scrubs also appear in the Deku Palace and Woodfall. Like in Ocarina of Time, these Dekus do not attempt to be friendly with Link and can be destroyed in battle, usually leaving behind a Deku Flower for Link to use.

There is a mini-game specifically for Deku Scrubs located in North Clock Town, the Deku Scrub Playground.

Four Swords Adventures
Four Swords Adventures features a group of Deku Scrubs living in the Lost Woods. These Deku Scrubs were awoken from their slumber by Ganon transforming the forest into the Lost Woods. They look forward to the expansion of the Lost Woods to cover all the forests of Hyrule, at which point they can travel freely. If someone gets lost in these woods, they are said to transform into a Deku Scrub. Despite being tied to the woods, they are able to travel beyond the forest using underground passageways, and later appear in Frozen Hyrule where they have taken to a new game they call Terrorpin Hockey. Despite working for Ganon, none of these Dekus will attack the four Links, and will speak freely with them, assuming they are not a threat.

Weaknesses
Dekus can deal with water, but if they happen to venture in deep areas they will hop on the water to survive drowning. Like plants, too much water can hurt them. Luckily, Dekus are usually light enough to stand on lilypads, granting safe travel over the swampy waters that the Dekus of Termina call home. In Deku form, Link is able to skip across water, but can not swim. Dekus are also highly flammable, and rightly so, as they are wood-based creatures.

Trivia

 * Dekus have a unusual way of speaking that often involves making the noise "pi" after sentences. This was removed from the translations of most games, but was left intact in some instances such as in Four Swords Adventures.
 * Octoroks share the same method for defeat as Deku Scrubs in and other 3D games. In SS undefined they appear on land and hide in bushes, giving them an appearance very similar to a Deku Scrub, but Dekus do not appear in the game.