I can tell you that I practically use Suppression Grenade and the Flashbang for my titan classes, they are awesome! To answer your question the grenade makes it so that they can not use their jumping ability (ie blink, double jump, glide, jetpack) it will also neutralize skills that are currently active. I have fought many gunslingers that use their golden gun, the second that I see them use it is the second I throw the grenade out, and bam, they no longer have it. As for how many shots that they have left, I have never gotten hit by the suppression while in my golden gun on my hunter. Best time i ever used suppression was on Venus pvp, bounced off a wall landed on the little jumping platform, the people on the platform couldn't jump away.