With that naturally gigantic Speed stat, a Speed boosting Nature, a Choice Scarf, Swift Swim in rain, perfect Speed IVs, and 252 EVs in Speed, just how fast can Barraskewda be?
Please don't include Speed-boosting moves like Agility and Acupressure.
I did a battle with a Choice Scarf Barraskewda and Jolly with Pelipper next to it, so it should've been its max Speed.
Hope this helps! :)