The Green ChuChu can be found in five Zelda games, but their appearances and purposes are very different in each. In Majora's Mask, a defeated Green ChuChu drops a Magic Jar, but acts the same as a Red ChuChu. In The Wind Waker, a Green ChuChu drops Green Chu Jelly which can be made into a Potion that restores Magic Power. Green ChuChu also appears in The Minish Cap and Phantom Hourglass. Green ChuChu also appears in Twilight Princess, but their jelly is virtually useless. Green ChuChu can shrink into a puddle and avoid attacks, but they are easily defeated with a swipe of the Sword.
That's a Green Chuchu.
The green variation of ChuChu is one of the first Link encounters. They contain Magic Jars if Link manages to defeat them. These are particularly useful if Link is running low on magic. They are found in Termina Field, Great Bay Temple and Stone Tower Temple. They can be defeated with almost all of Link's weapons and re-spawn after a certain amount of time.
The Wind Waker
Green ChuChu is the second form Link encounters, and probably the most common variant of them all. They mostly inhabit forested areas such as the Forest Haven or Forbidden Woods. They can be pretty annoying before Link obtains the Boomerang, because they have the ability to turn into blobs, which makes them unable to be affected by Link's Sword. Once Link obtains the Boomerang, he can use it to stun them, which makes them a piece of cake. They take two hits to defeat with the Hero's Sword and one hit with the Master Sword.
They usually drop Green Chu Jelly when defeated.
The Minish CapThe Minish Cap, found within the Minish Woods. They appear as a small blob on the ground and then shows their entire body. They sway back and forth and occasionally jump toward Link. Two sword slashes defeat a Green ChuChu.
The only method of attack that the Green ChuChu employs is by making contact with Link via their leaping towards Link. When the ChuChu makes contact with Link, it deals 1/4th a heart of damage.
Green ChuChu is very rare. They are only encountered in the Temple of Courage. They have the ability to dodge attacks, so stun them with the Boomerang before attacking.
Target lock: Green Chuchu
The small variant of this Greenish Blue ChuChu is first found in the Waterfall Cave on Skyloft. They also appear in Faron Woods and Lake Floria. These ChuChus slowly move toward you, then gnaw on your leg when it gets close enough. One sword slash is enough to defeat it.
The large variant is found in both Skyloft (at night) and the Ancient Cistern. Hit them with a vertical sword slash to separate it into two parts, then defeat each part individually.