You'll notice neither the Smogondex and Bulbapedia are on the list of acceptable sources for accurate game mechanics. -_-'Ok so a friend of mine, user ShellShocker, and I did a test battle because he suspected that Imposter copied ivs- which, according to Smogon and Bulbapedia, it shouldn't. During this test, I used a team of 6 Dittos with imposter and 2 ivs in Speed. He used a team of 6 Brelooms, with 31 ivs in Speed. We battled. This is the log.
http://pokemonshowdown.com/replay/customgame10901191
So in the battle, my 2 ivs Ditto outspeed his 31 iv Breloom quite a few times- both while using priority and non priority moves.
I think this is enough evidence that there is a bug.
The correct answer is that while IVs aren't directly copied, the stats after IVs are copied straight-up.
Your IVs and Nature probably played a role.http://pokemonshowdown.com/replay/smogondoubles10911590
Turn 9, Marowak somehow outspeeds my Camerupt in trick room despite me having lower speed (76 vs 80 something).
Cost me the game :(:(:(:( that fawkin hypnosis ended up fking me over and camerupt fainted instantly..