I actually haven’t played continued playing my savegame (haven’t touched it since before Mewtwo was added), but when I played, I pretended to be a Team Rocket member using this, with Nidoking as my main Pokemon. Being one of my favorite mons, I thought of doing something “special” for him. At first I thought of messing around with the game code and making a custom delta with Poison/Dark typing and while I could have done so, it was too much work making him future-proof for further delta updates. Thus I ended up just modifying the shiny sprite and turning it into this:
As you can see, I tried to make him meaner by increasing spike/ears/horns sizes, changed arm/leg shapes, etc.; all with some design throwbacks to Nidorino and Nidoqueen. The colors are not only related to his original “supposed” typing, but also used to match my Team Rocket sprite.
If anyone is interested in using it in-game, let me know, I’ve got the files properly named in my Insurgence backup folder somewhere.