In sport BJJ most of the standard judo and wrestling throws are legal even if they may look like a slam.
Many BJJ federations do not clearly define the difference between a slam, a throw/ takedown.
The rule of thumb is that the takedown should be performed in a continuous motion, the natural force of the movement is allowed. Also you cannot lift your opponent in the air, pause, walk around then slam the opponent on the mat.
Check out the joke video:
