Darkside

The Darkside is a Pureblood Heartless that is found in Kingdom Hearts, Kingdom Hearts: Chain of Memories, Kingdom Hearts 358/2 Days, and Kingdom Hearts coded. It is one of the bosses at the Awakening, Destiny Islands, End of the World, and Twilight Town. Its theme song is Destati.

Kingdom Hearts
''Enormous Heartless that appeared in Destiny Islands with Shadows. It led the Shadows in the battle against Sora when he first received the Keyblade. Although Sora defeated it, the island was swallowed by the darkness.''

Kingdom Hearts: Chain of Memories
The Heartless that attacked Sora's home, Destiny Islands.
 * Sora's Story

Sora fought valiantly to protect the islands and his memories there.

''The Heartless Riku attracted when he was seduced by darkness. It destroyed Destiny Islands.''
 * Reverse/Rebirth

Zexion called Darkside in order to subdue Riku.

Kingdom Hearts 358/2 Days
This giant Heartless will devour all around it if left unchecked.

''The dark homing blasts fired from its chest can be turned back on it with a block. Target its hands or, if possible, its head.''

TIP: Earth-based attacks like its homing blasts can halve your current HP.

Kingdom Hearts
Sora also glimpsed a number of Darksides within the Door to Darkness before they were destroyed by King Mickey.

Kingdom Hearts 358/2 Days
Darkside is fought at Twilight Town (during a mission involving Roxas and Xion) in Kingdom Hearts 358/2 Days.

Kingdom Hearts: Chain of Memories
In Kingdom Hearts: Chain of Memories, Riku fights a Darkside similar to how Sora fought him. Zexion creates this Darkside from a copy of Riku similar to how Sora faced Darkside in Dive to the Heart where it was created from Sora's shadow.

Kingdom Hearts II
It appears in Sora's memories when Roxas was dreaming about them.

Kingdom Hearts coded
A data version of the Darkside appears in Kingdom Hearts coded, which is battled by Sora.

Kingdom Hearts
Darkside is an easy-medium boss, and you can defeat him very quickly. His weaknesses are his head and hands. His attacks in all three battles of Kingdom Hearts are:
 * Darkside punches the ground, causing a dark pool and mild shockwave to form. This attack gives birth to a small number of Shadows.
 * Darkside scoops up an orb of darkness, which splits into many smaller orbs that rain from the sky.
 * Darkside creates a dark force in the heart-shaped hole in its body, which shoots homing dark missiles. These can be dodged by standing behind the massive Heartless, or reflected back at the Darkside for major damage.

This is simply a hack-and-slash battle, with no real strategy needed. Simply attack at every opportunity and avoid Darkside's attacks. If you get low on health, defeat the Shadows he spawns as they drop HP orbs, or Cure. If you can climb Darkside's arm and attack his head, you get tech points for every combo finisher landed.

Trivia

 * The Darkside battle shares many similarities with Twilight Thorn, a gigantic Nobody. Both appear in Roxas and Sora's Awakenings, respectively, and are the first bosses of the game. Their Japanese names, Twilight Zone and Darkside, are both science-fiction horror serials.
 * In Kingdom Hearts, Darkside had a flap of skin where the heart on his body creases at the top. In Kingdom Hearts Re:Chain of Memories this flap of skin was removed for unknown reasons.
 * The first Darkside battle is the only boss battle in the series in which Sora doesn't speak.

Darkside Schattenborn