Graziano's court-appointed guardian... one Peter Musante... filed papers yesterday alleging that Hulk and his wife LINDA should be held responsible for crash. Their 17-year-old son, NICK HOGAN, who was driving at the time, was also named in the suit.

The Grazianos are suing for damages "in excess of $15,000".

The suit claims that Nick negligently operated his Toyota Supra by racing another man in a Dodge Viper... A Viper that was owned by Hulk Hogan, by the way.

As for Hulk and Linda, the lawsuit claims they knew their son was a reckless driver, and that he had fixed up the Supra for the purpose of racing. But not only did they do nothing to stop his dangerous behavior... they ENCOURAGED IT.

And the lawsuit states that Hulk should have known Nick was driving under the influence at the time of the crash... because he's the one who supplied the alcohol in the first place.

The lawsuit also names Daniel Jacobs... the man who was driving the Viper. He has pleaded no contest to reckless driving. Nick Hogan is facing a felony charge of reckless driving with serious bodily injury.

Graziano remains in a coma... and no matter what happens, it's pretty much a guarantee he'll require medical care for the rest of his life.