Peahat

The Peahat is a common enemy that has recurred over different Zelda games. Generally, it has kept the same form, but its behavior and functions have changed drastically over time. It resembles a flower/plant-like creature, similar to a pineapple or bush, with leaves either at its base or top that function as helicopter blades, making it flight-capable.

The correct typography is Peahat, as confirmed by the official website, the manual for The Legend of Zelda, and the in-game Figurine Gallery of The Minish Cap. Pea Hat was used in Majora's Mask.

The Legend of Zelda
In The Legend of Zelda, Peahats are the spirits of dead flowers, fluttering around the screen in packs. Orange-colored, they flutter about the screen and can only be harmed when they stop moving. While resting, they are vulnerable to the sword, arrow, or bombs. They are resistant to fire and the boomerang, even though some enemies are stunned by the boomerang.

Link's Awakening, Oracle of Ages and Oracle of Seasons
Peahats return in Link's Awakening, where they behave in the same exact way as in The Legend of Zelda but only come in one color.

Peahats in the Oracle series are almost identical to those from Link's Awakening and are defeated in the same manner.

Ocarina of Time and Majora's Mask
In Ocarina of Time, Peahats got a major overhaul. They grew to ten times the size of Link, moved their blades to their base, and became solitary creatures. They were only seen in the southern and northern corners of Hyrule Field, away from the paths and crossroads, making encounters with them uncommon. During the night, they slept buried in the ground, only revealing the blossom on its top. During the day, they emerged. Only one Peahat is found in Majora's Mask, in a hidden hole in Termina Field. Their behavior is also more passive and calculated, rather than randomly flitting about, when comparing to the precendents. When approached, they shoot up into the air and hover over Link using their helicopter-like leaves to stay aloft.

Then they will either spout Peahat Larva from their blossom, which buzz around Link like insects and attack, or they will swoop down and attack him with their blade-like leaves. If attacked at night, Peahats will only spout Peahat Larva and not emerge.

A Peahat's vulnerable point is the root, so a well-aimed shot at its bottom with a slingshot or bow will take it out. Its spinning blades make it nearly invulnerable to a sword or other melee attack, but it is possible the destroy with repeated slashes to the root if Link manages to get past their spinning blades. Peahats can also be killed during the night in Ocarina of Time by continuously exploding bombs at close range. However, using bombs will provoke the Peahats into releasing Peahat larva, which will attack Link with no mercy.

It is confirmed to be the only creature in Ocarina of Time capable of dropping two different types of loot at the same time, although it does this on an uncommon basis.

Peahat Larva
Peahat Larvae in Ocarina of Time are emitted by sleeping Peahats in Hyrule Field at night or by a Peahat that has flown high into the air. They attack from above and if they land, they die. They will continuously chase Link if not avoided or dispatched. The shield can fend off these enemies. If not killed, Peahat Larvae eventually get tired and return to their parent plant. Peahat Larvae appear in Majora's Mask when Link strikes at the lone Peahat in the hole in Termina Field at night.

Interestingly, Peahat Larvae are closer to the size of the Peahats from the original Legend of Zelda than the normal Peahats in Ocarina of Time.

The Wind Waker
Peahats are found all around the islands but congregate in the Forbidden Forest. They are smaller than they were in Ocarina of Time (see also: Seahats). They are more aggressive and come in packs of about two or three.

Their helicopter leaves have migrated to the top of their bodies, and they use these to defend against sword hits as well. The Bow will defeat them in one hit. Also, their leaves can be disabled by the Deku Leaf, the Hookshot, or the Boomerang, leaving them vulnerable to melee attacks. If left alone, they will grow new leaves. Upon defeat, the Peahat will sometimes drop a Golden Feather, an item for the Spoils Bag which is a valuable for a side quest involving a Rito sentry. Using the Grappling Hook on them will also result in a Golden Feather.

The Minish Cap
The Peahats are impossible to hurt with the sword in The Minish Cap (except for a spin attack from the completed Four Sword), but the Gust Jar can suck them in or the Boomerang will stun them, allowing Link to attack with his sword, or shoot them into walls. Another effective weapon is the Bow and Arrow. The green Peahat cannot be harmed by a sword because it hovers above Link, waiting to drop the bomb. The best thing to do is wait to see if the bomb will blow up the peahat as well, or try a Down Thrust.

Twilight Princess
In Twilight Princess' incarnation, Peahats have ceased to be an enemy and are now a tool or helper for Link. Their appearance is similar to The Wind Waker but with a more realistic appearance. Their bottom root is more sac-like, resembling a burlap ball or a cactus.

They float in the sky and are invulnerable to any weapon. Their only purpose is to act as targets for the Clawshot to advance over large gaps. Mainly, they are found in either the Gerudo Desert or the City in the Sky (where they play an extremely important role in progressing through the dungeon and during Link's battle against Argorok). These Peahats stay aloft when carrying Link, but if he equips his Iron Boots, the weight is too great, and they will start to descend.

In Link's Crossbow Training, Peahats appear in Level 5, which takes place in The City in the Sky. Although the main objective of this level is the shoot the targets carried by Oocca, the Peahats in the background may be shot, which will cause them to descend sligthly and give the player 1 point for each time they are shot. Shooting them with Bomb Arrows, however, will completely destroy them and will grant 100 points. The very last one that appears will reveal a Red Fairy worth 1,000 points if it is destroyed with a Bomb Arrow.

Skyward Sword
Peahats appear in several areas in Skyward Sword. They serve as Clawshot targets, similarly to their Twilight Princess counterparts, and are seen most prominently in the Lanayru Desert region.

Submerged Peahats can be found in the game underneath the ground in certain areas. They can be activated using the Whip to pull them up.

Zelda's Adventure
Peahats in Zelda's Adventure act more like Octoroks than their canonical kin. They never fly, opting to instead wander around in small groups on the ground. They've also developed the ability to shoot seeds. Early in the game, when Zelda's life meter if low, these are the most deadly enemies as they have high resilience and usually travel in groups of 2-6 members. However, once Zelda has obtained the Magic Shield, she'll be able to block their projectile attack, making them easier to defeat.