No, partner commanders can be different colors
However, I understand some people do not like playing with joke cards, even in a casual format like Commander
Honorable Mention #3 - Nissa's Victory It's very simple
For six, your Commanders now have a power and toughness of 10 each, nasty for the game-winning
Sacrifice Outlets The best sacrifice outlets are permanents with activated abilities that cost no mana and have no timing restrictions, like Altar of Dementia and Phyrexian Altar, which provide good value on their own and enable various infinite loops
It does everything a creature does, like hit opponents, have abilities that help your other creatures hit opponents, and so on