Kingdom Hearts coded
After defeating a mind-controlled Data-Riku, Data-Sora jumps inside his data in an attempt to rid the bugs that Pete had planted inside him. However, in the process of doing so, Data-Sora's own power was lost and distributed in the form of Matrix Power. Eventually, he regained his own power and vanquished Data-Riku's bugs, stabilizing both of them.
In Kingdom Hearts Re:coded, Matrix Power is recovered by obtaining blue data prizes, which are dropped when prize blox are destroyed and Prize Bugs are defeated. The amount of Matrix Power recovered is shown by a percentage, in the top left corner of the screen. For every percent of Matrix Power recovered, the Stat Matrix, which has no power at the start of Hollow Bastion II, regains 1% of power. So, for example, at 0% Matrix Power, the Stat Matrix provides no stat bonuses, and Data-Sora is left at level 1. At 100% matrix power, however, the Stat Matrix is fully powered and provides all the bonuses it would normally.
Data-Sora can only recover a set amount of Matrix Power in each "world" within Data-Riku: 20% at Destiny Islands, 40% at Traverse Town, 60% at Wonderland, and 80% at Agrabah. However, he does not need to recover the full amount of Matrix Power possible, to clear a world. Once he defeats the fake Data-Riku within the Chapel, his Matrix Power is restored to 100%, regardless of how much he recovered beforehand.