Now, since it's casual, it's all fun and games, right? Well, some people just want to be a spoil sport, and that ruins everyone else's idea of a good time.
Obviously if it is banned I'm regular EDH, you cannot play it here. I mean, come on, Animar, Soul of Elements + Emrakul, the Aeons Torn
is just straight up broken.
Mana:
The coloring of your commanders must align slightly, unless they are 1c.
1c/1c - Any
2c/1c - Any
2c/2c - 1 alignment
3c/1c - Any
3c/2c - 1 alignment
3c/3c - 2 alignment
4c/1c - 1 alignment
4c/2c - 2 alignment
4c/3c - 3 alignment
5c - everything will align with a 5c creature
If your playgroup doesn't want to deal with color restrictions, that's fine, they are included here as a recommended guide for 4-color enabler and so everyone doesn't go and play 5 color jank. Go nuts and build funky magic.
You broke the game:
This will be a list of sets that you cannot run together as your commanders for the simple reason that they break the game to make it unfun (new word). I don't want to have this list, but you could have the other card in your deck (if it fits), and draw into it/tutor it.
Aurelia, the Warleader + Brago, King Eternal has infinite attack steps
Oloro, Ageless Ascetic
+ Karlov of the Ghost Council
Gisela, the Broken Blade + Bruna, the Fading Light
If you find an addition to this list, please tell me and I will add it.