Dr. Gero and Android 19 were menaces in Sparking! Zero, terrorizing DP battle in ranked and online tournaments before they got nerfed. A short documentary on said characters at their strongest: https://www.youtube.com/watch?v=1DmWBcIPRI0
I wouldn't call them menaces, just major annoyances due them not losing ki when they flew, which let players cheese matches via time out. So glad they were nerfed.
