Anti-Riku

Anti-Riku (アンチリク) is a dark version of Riku that is found in Kingdom Hearts 358/2 Days. It appears in the Mission Mode version of Mission 93: Believe, replacing Riku at The World That Never Was. It is similar to Anti-Saïx.

As it only appears in Mission Mode, Anti-Riku does not exist in Kingdom Hearts canon.

Strategy
Anti-Riku uses the same battle techniques as Riku. At the start of this battle, The player should immediately Lock-On to the boss. This should aid the player in keeping track of him, as Riku is fast. As soon as this is done, the player should attack Anti-Riku in the back. The player will not be able to deal damage if Anti-Riku is attacked from the front, as the boss will utilize Dark Shield and block them. A majority of this battle will be following this Anti-Riku around the battlefield in front of Memory's Skyscraper.

When the player gets close to Anti-Riku, he will attempt a series of thrusts with the dark Oblivion Keyblade it wields. Anti-Riku may also launch a Dark Firaga attack if the player is not within close range. When Anti-Riku's HP starts to diminish, he will begin to utilize a Dark Break-style desperation attack. This can be dodged via the Glide ability or if the player can start a fast run. Just when Anti-Riku's HP is about to hit zero, he gains access to his Limit Break, Darkstorm. Anti-Riku will jet around the battle area, unleashing columns of black flame at the combo's end. The player can time this attack to when the boss's weapon begins to glow with a white-blue energy.