Alright so here's why this works.
the way trick room works is while calculating your speed, if trick room is active, it instead takes 10000-(your pokemons speed) and uses that. this means if you have lower speed, you'll end up with higher speed.
however, there's an extra step afterward that conflicts with this. I'm not entirely sure why this step is here, but if a pokemon's speed is ever greater than 8191, the game subtracts 8192 from it. Maybe a way to keep super high numbers from overflowing? who knows. In a trick room, normally EVERY pokemon is effected by this, and they all get the -8192.
regilecki is in the range for easily having enough speed to do this from just tailwind and choice scarf.
any pokemon that can boost themselves to over 1808 speed will break trick room and go first anyways, and have done so since black and white.
https://glitchcity.wiki/Trick_Room_glitch 
