AntiSora

The Anti-Sora was a shadow duplicate of Sora that Riku created to show his power of darkness to Sora. It appears in Kingdom Hearts, in the Neverland world. Additionally there are regular enemies in Neverland called "Shadow Sora", whom are merely darkened models of Sora without keyblades; they are very weak but have high HP, and their attacks make you lose massive amounts of munny. However, they in turn drop loads of munny and HP balls when defeated. Sora's Anti Form in Kingdom Hearts II closely resembles Anti-Sora, with a few aesthetic differences. However, Anti-Sora only refers to the boss that is fought in Captain's Cabin.

Kingdom Hearts
Sora meets up with Riku in Neverland, where Riku reveals he now has control over the Heartless. To prove this, he creates a Heartless version of Sora before Sora's eyes. Sora encounters these Shadow Soras several times throughout his adventure on Captain Hook's ship, although they have no weapons and often disappear before he can destroy them. Only Sora is able to damage these enemies, and none of his partners will attack them.

When Sora makes his way to the captain's quarters, Riku creates Anti-Sora, an exact clone of Sora with large, yellow eyes. Anti-Sora used the same keyblade attacks as Sora, but could also become a shadow like the namesake enemies. When Sora defeats it, Anti-Sora falls back into darkness, dropping the Raven's Claw on the way.

Kingdom Hearts
It has similar physical properties as Sora. However, it is unable to use magic, instead using abilities of what one might suspect a shadow would have, e.g. being able to flatten itself and move on surfaces in that state. After depleting about half its HP, Antisora creates two copies of itself to distract you, but only the original can take or do damage. Antisora can also vanish into the ground and pop out underneath Sora, doing high damage. Your prize for winning is a Raven's Claw accessory.

Trivia

 * Anti-Sora is one of only few characters who do not have entries in Jiminy's Journal (the other two being Chernabog and Glut).
 * Anti-Sora strongly resembles the Anti Form from Kingdom Hearts II, except for the fact that Anti-Sora's outfit is purely black,(but you can still see his details in his clothes,but not any in his face to show that he is a Sora clone) while Sora has grayish flames on his black pants while in Anti Form and has blackish flames from his legs and hands unlike the dancing Anti Sora.
 * Anti-Sora is, in a way, mirrored by the Shadow Roxas that appears in Kingdom Hearts II.

Anti-Sora