You mean running straight up walls?
He's done that as early as KH2, with both Sora and Roxas running straight up the side of Memory Skyscraper in The World That Never Was, in their respective fights with Xemnas and Riku.
In DDD you had free parkour to bounce off walls, grind railings, and swing on poles. Flowmotion carried over from that into 3.
Characters have always been able to defy physics with huge jumps, falling long distance, teleportation. KH is similar to DBZ in this regard, where even human characters are able to fly.