Namco never gave any permission, to American users, anyways.
In Japan you'd still need to buy a licence to use the assets, and you wouldn't be able to recreate the games they come from.
Technically, everything is copyrighted that is a work, though you need to actually have some legal stuff to take legal action. Some will be in the public domain and thus you can use it, but for the most part, just come up with original ideas before just copying sprites, or at least check to see if you need to come up with an original idea/original artwork.
