Data-Riku is a boss who is fought in Kingdom Hearts coded and Kingdom Hearts Re:coded. A stronger bugged form of him appears on the 100th floor of the Avatar Sector in the Avatar Menu of Kingdom Hearts Re:coded.
During the first phase, Data-Riku only has a small selection of moves, which he doesn't use in quick succession - just some simple lunges and slashes that can be blocked or avoided with the correct timing. He will sometimes put up a Dark Shield, similar to in Kingdom Hearts 358/2 Days, and it will react in the same way: Data-Riku will use a counterattack if Data-Sora hits the shield from the front. He will also stand still for a moment after putting up the shield, in an attempt to bait out an attack. This is a good opportunity to attack him in the back, which will ignore the shield, or to retreat and heal until Data-Riku starts moving again. Data-Riku will also sometimes interrupt physical combos, shouting "Keep trying!" after doing so. Hitting him again in this state will cause him to instantly counterattack, so it's best to retreat for a moment so the status can wear off.
As most of Data-Riku's attacks are close-quarters, strong ranged commands such as Triple Firaga or Judgment Triad can be used to safely deal damage from afar. Otherwise, hit-and-run tactics and unfinished combos tend to be safe to avoid Data-Riku's counterattacks.
In the second phase, Data-Riku gains access to a new attack. Sometimes when there is some distance between Data-Sora and Data-Riku, he will teleport above the ground near Data-Sora and slam his Soul Eater below, sending seven Danger Blox and a Prize Blox outwards. While the Prize Blox poses no threat (and can actually be broken for some HP prizes), the Danger Blox can deal damage. Use the same strategy as before, blocking then attacking and using projectiles whenever possible. If Data-Riku teleports into the air, quickly Dodge Roll or Air Slide away to make reacting to the Blox easier. It is possible to jump over the Blox at closer range, but this has tight timing.
Another strategy to overcome this technique is to immediately Lock-On to him after he teleports - this way, Data-Sora can easily see the Danger Blox coming and dodge them appropriately. The map on the touch screen can also be utilized since Blox are colored grey on the map, offering another visual cue.
In this phase, Data-Riku stops holding anything back and his stats improve. His strongest move Dark Aura, is now put into play. Similar to how it used in Kingdom Hearts and Kingdom Hearts: Chain of Memories, Data-Riku performs five teleporting lunges before finishing with a slam that sends out a pulse of energy. While it is possible to damage Data-Riku during this move, it is still best dodged as it is hard to tell where he will emerge next.
Be prepared for it when he rises into the air and shouts, "Just try to keep up!". Count out how many times he teleports, avoid the attacks with Dodge Roll, and after the fifth lunge, immediately jump to avoid the finishing slam. Block can also be used to defend against his teleport rush attack, but the ability Round Block must also be learned, and his finishing move can't be blocked. He can also fire three Dark Firaga, which can be blocked easily. He uses the same attacks as the previous phases, to be sure to block or dodge accordingly.
While debugging Data-Riku, a portal opens to a facsimile of the Chapel, where the Bugs have taken Data-Riku's form. This Data-Riku follows the same pattern as the Third phase, but he has an extra bar of health.
A bugged version of Data-Riku appears on the 100th floor of the Avatar Sector. His patterns are once again the same as his Third phase (meaning he has immediate access to Dark Aura), but his stats are drastically increased. His Danger Blox attack no longer has a Prize Blox (it will send out 8 Danger Blox instead), and this version of Data-Riku doesn't speak, so visual instead of audio cues will need to be used for dodging attacks.
Additionally, Data-Riku's bugged aura will change as his HP decreases, granting him further stat boosts. He will start out normal (blue bugged aura), then gain a speed boost (yellow aura), then gain a strength boost and immunity to stagger (red aura), and finally grow to a giant size (green aura). The green aura will also double his max HP, but since he can't heal himself, that isn't an issue. Note that the terrain for this fight will be bumpy instead of a flat room, limiting the space that Data-Sora has to work with.
Since this takes place in a System Sector, there is also a floor challenge to use a Finish Command within 60 seconds. Unlike the bugged Data-Roxas, this bugged Data-Riku can't rewind Data-Sora's clock, so building up enough Clock gauge can be done easily with some long-ranged commands. Alternatively, bringing and using a Megalixir will grant access to the Finish command immediately.