cards that change type yugioh Synchro may be 1st or Unlimited Edition Yu-Gi-Oh! - Star Changer (GENF-EN059)

Phyrexian Fleshgorger is huge and painful to remove thanks to ward, but also just a pile of stats on the battlefield with little extra utility

And even then, it's often Pokemon, then Trainers, and finally Energies go wherever there's space on the mat

Though it makes me think people won't let you untap with her on the board, since you could easily drop a Triumph of the Hordes or a big green pumper or whatever

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