Gyo was introduced in the Heaven's Arena arc. Gon used it to see Hisoka's Bungee Gum in their fight while Machi and Wing did the same thing to see through Hisoka's In which was then taught to Gon, Killua and Zushi as they replayed the fight to learn to see through his In. So it was already a concept that existed before and during the Phantom Troupe arc and the Spidera are top tier Nen users, if Machi could use it. There is no reason to suspect the others couldn't do it either. Assuming they couldn't, Machi should've been enough. To see through his tricks at one point but at another time forgetting to use it is an amateur mistake. One that Bisky made sure to correct about Gon and Killua by making them use Gyo everytime she pointed her finger. The Phantom Troupe aren't amateurs, they're professionals.