It typically includes content from later in the Shippuden series that wasn't in the original PS2 games, such as:

Because the game does not exist, any website claiming to offer a "Storm 6 PS2 ISO" is highly likely to be fraudulent.

Modders in the community take the engine of Ultimate Ninja 5 and swap out textures, models, and move-sets to simulate newer content. When you download a "Storm 6" ISO, you are usually getting:

(The peak of PS2 Naruto games) Naruto Shippuden: Ultimate Ninja 4 Naruto: Ultimate Ninja 3