Speedrunning is something I'm just getting into in the Kingdom Hearts community. Its really amazing seeing all these people do crazy strategies to get the time down even just a second. I hope to one day do a complete Data Org run in under 40 minutes. Normally this fight would take about 6 minutes, but I managed to skip the last 2 segments of the fight completely. So I only fought him on stage 1 of 3. The way this strat works is by abusing limit form, Ars Arcanum, and Elixirs. It stun locks Roxas and doesn't allow him to retaliate. Elixirs also allow me to refill my magic and thus keep spamming Ars. Well, that's the simple explanation, its quite harder in practice.
For this fight I was level 99 with 72 Magic, 69 Strength, and 70 defense. I was also using Decisive Pumpkin because it has the strongest damage output with the ability combo boost. I cant go faster until I raise my strength to level 80 (max damage output on a boss). If I take time to raise it I have no doubt I can pull under a minute, that's if Ars Arcanum doesn't keep dropping mid-combo of course. Enjoy!