New event?

I am just askign if this is possible please do not post unecessary posts.

Is it possible to take files like say the [Slime] monster, edit it with a new name and more stats, maybe a different look, then add it back to the files (not replacing slime but as a new monster) for monster surviving events?

like this for example, but in this one it's bugged or it replaces the hero slime.
https://pintosonline.activoforo.com/screenshots-f6/slime-god-event-t240.htm

that would be cool :3 BTW Slime God FTW, hardest monster on Pintos online <3 please dotn remove it