Well, I just thought it would be bounced to the user itself (as though the "user" and the "foe" were the same), thus it wouldn't affect the target at all...I can't see why it wouldn't affect all hazards on the field.
I get "The Battle Video couldn't be found."
I primarily used Mega Aerodactyl (174 lbs. 79.0 kg) but as of this post Ive also tested using dragonite (463.0 lbs.210.0 kg) vs Tyranitar (445.3 lbs. 202.0 kg) and Virizion both were unsuccessful. Suicune however was successful (412.3 lbs. 187.0 kg). So at this point it is all but confirmed that the weight limit is static. The only pokemon left to test to find the exact weight limit are Bronzong, Entei, and Ho-Oh. As a side note, I was able to pick up Registeel with the ability light metal.Ash_F2D what was your Sky Dropper's weight? I'm curious if that is put into effect as well.
Okay, something totally bizarre happened in a Triples battle I accidentally did yesterday. In the battle, I was facing a team based around Round. A Scarf Porygon-Z led with Round, and then both the Sylveon and Aurorus seemed to get priority from it, as they outsped my Manectric. HOWEVER, later on in the match, he used Round with Mega Gardevoir, Reuniclus, and Porygon-Z. The odd part is that THIS time, Reuniclus went AFTER my Pokemon.
So TL;DR: I think something else is effecting Round's priority in a way we don't know of yet.
Here is the battle video for those of you that want to see it: 8EAG-WWWW-WWW5-E849