Jay Glazer gets hit a lot at his MMA gym -- whether it's UFC stars or big name actors, dude gets beat up all the freakin' time ... but who hits the HARDEST??

Star-Lord!!!!

That's right ... Chris Pratt's got the power that'll knock anybody out, so says the Unbreakable Gym owner ... who tells TMZ Sports Pratt straight-up hits harder than the Natural.

"It sucks getting hit by Chris Pratt more than it sucks getting hit by Randy Couture."

UMMM ... HAVE YOU SEEN RANDY COUTURE FIGHT?!?

FYI -- Couture is one bad dude ... he's got a 19-11 record and has 7 knockouts under his belt. Oh, and was a 3-time UFC heavyweight champion!!!

So ... does this mean CP will ditch Hollywood for the Octagon?? Not so fast ...

"He's too busy being happily engaged and pretty."

BONUS -- we also got an update on that tooth Demi Lovato knocked out of Glazer's grill a couple weeks ago ... and super glue really does fix everything!! (We sure hope he's kidding).