In the early days of Pioneer, players referenced previously dominant Standard decks as a baseline for Pioneer usage
Honorable Mention 2 No Mercy I am a sad Abe that this did not make the Top 10
In Standard, it can be cast on Turn 2 after casting either Gilded Goose or Arboreal Grazer, and it plays particularly well with either one, in that Oko and Gilded Goose each make Food for the other one, so you can keep making mana or keep making Elks as needed, and with Arboreal Grazer, you can immediately turn the Grazer into an Elk and attack for three on Turn 2
Now arguably, we do see a drop in popularity of Selesnya humans in favor of the other Selesnya deck, Life gain Combo, but that I think has more to do with a card that Alchemy brought in which we will talk about next
Partner (You can have two commanders if both have partner.) 1/3 Illustrated by Square Enix Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Legal Modern Not Legal Brawl Legal Legacy Legal Comp
From Commanders most humble beginnings to becoming the most popular way to ever play Magic, specific cards have been the drivers of the formats evolution, sometimes in unexpected ways
