Of course, Zion has been legendarily rattling rims since he was a high school prodigy ... and now that he's on his way to the NBA, we had to ask Blake if Z can be one of the best dunkers ever.

Blake's opinion? He says there's no doubt in his mind Zion can be up there with Michael Jordan and Dominique Wilkins, telling us, "100 percent. 100 percent."

"If he keeps playing like he is, he's going to be a monster."

In fact, Blake seems to be a huge fan of Zion's game overall -- not just his dunking -- saying, "He's a really good basketball player ... he can do a lot of stuff. He's going to be really, really good."

As for Griffin's advice on how Zion should handle possibly participating in the dunk contest in his rookie season next year ... BG says the ex-Duke star should only do it if it feels right.

But, when Z eventually decides to compete ... Griffin says it'll be a show, telling us, "He's probably going to do some things that we haven't seen in a while."

#CantWait!