If a card specifically states that it moves Commanders from the battlefield to the Command Zone, anything that's been mutated onto your Commander moves along with it, then falls off - and will probably be stuck there, since there's no way to cast non-commander creatures from the Command Zone
Brightcap Badger Bloomburrow Commander brought Brightcap Badger and the spoils of saproling support, so suffice it to say this is solid
The mechanic continues to show up both in-universe sets, even in the prepare spell on Paradox Shaper, in the middle of mana costs like on Abstract Paintmage, and in Universes Beyond sets on specific characters like the dark-side of Katara on Katara, Seeking Revenge
From then onward, lands have kept their same basic (pun!) look
But Meteor Golem enjoys hanging out with other commanders
SBA are performed