However, you can always use cards with cycling like Lrien Revealed at the end of your opponents turn to fetch a card, and, more importantly, exile the card on top of your library to play it on your turn with no restriction
That said, with the right commander at the helm, its still very much doable
There is (at least in theory) supposed to be a drawback to playing multiple colors by limiting the consistency of your access to the different types of mana, which you have to address by filling more of your deck with fixing
It's a shoe-in for blink decks, and goes ballistic when paired with Displacer Kitten
Jetmir, Nexus of Revels This fat cat (complimentary) encourages you to go wide with pride
4 Jared Carthalion, True Heir An odd divergence from other monarch commanders on this list, Jared Carthalion, True Heir doesnt make you the monarch when he comes into play, instead crowing an opponent and making it so you cant take it from them this turn