This was a fighting game with SD (super deformed) characters, and in the story mode you fight through challenges to get items that you can equip for power-ups. I think it had really simple controls, and one of the characters may have been a robot. The "human" characters were asian-looking. If anybody has played this and remembers the title, please post it here. I rented it once and forgot about it for a long time, but I remember I was obsessed with collecting everything.