My understanding was that Trick Room invents the Spd check to view lower Spd stat as higher and Vice-Versa. if that's not correct, then GB would be fine. but if the games Calculation checks a Spd Stat of 289 vs 57 as 57 being higher, then the difference between 289 and 57 would determine the power of GB. like i said i am not a programmer. that was just my understanding of a Spd check while under Trick Room.