I started a Free Battle. The roster was insane. It had characters that didn't even exist when the PS2 was in its prime: Sage Mode Kabuto, Tobi with the Rinnegan, and even a pixelated version of Minato. I picked Naruto (labeled "Naruto 6") and jumped into the Hidden Leaf Village stage.
"Naruto Shippuden Ultimate Ninja 6 PS2 ROM Work: A Community-Driven Project" naruto shippuden ultimate ninja 6 ps2 rom work
However, a fan-made exists for the PS2. This mod is built on the engine of Ultimate Ninja 5 and is primarily developed by the Narutimate Modding Team . Mod Features and Compatibility Naruto Shippuden: Ultimate Ninja 5 – Release Details I started a Free Battle