>>15365042It's only a personal anecdote, but I tested with Yveltal.
My 129 speed Malamar was out sped by a 31 Timid Yveltal only, did a few fights where I would KO an imperfect Yvetal to try and reroll his IVs and he would still be imperfect afterwards.
Also tested by KOing one with 31 speed and he still out sped after the first fight.