>>31368613DOOOOOM
They're good to get past mons that would otherwise counter you. A decent example of this is Groundium Z Sandslash-A in VGC to lure and nuke fire types that threaten it and Ninetales.
Also, some mons with unreliable STABs now get a powerful and reliable ZTAB, altough it is a one time use, it's still pretty good.
And then you got the option of a powerful nuke just for the sake of big damage and get a surprise KO.
