Workshop in Stadium is currently broken, which means this mode doesn't work

Stadium vs Non-Stadium Heroes

Have you ever wanted to play a Stadium game with heroes that are not enabled in it by default, against a team of either Stadium enabled heroes or non-Stadium ones? Well, now you can!*

*Please note that the non-Stadium heroes do not have per-hero powers available, only the generic items. Additionally, you can expect some minor (or major) bugs.

WARNING: After importing the code, make sure to NOT enable the Stadium checkbox in the Custom Game lobby (above players list)

By default, this Workshop mode forces Team 1 to use Stadium heroes, and Team 2 non-Stadium ones. You can change that in the Workshop Settings: