Vehicles, artifacts that need to be crewed to unlock their full potential as artifact creatures, have been part of Magic since 2016s Kaladesh
If a card that's already been on the battlefield for a full turn becomes a copy of something else, it'll still be unaffected by summoning sickness
Territorial Kazu The combination of fetch lands and triomes makes it trivial for Territorial Kavu to be a 2-mana 5/5 every game
But then he transforms into One-Winged Angel, and his power becomes all too clear
Once the stores receive their promo, they can use it at their discretion
The tokens didnt actually have Power and Toughness printed on them, so they werent perfect for game play, but it did mark the beginning of a practice that has continued to be used in mainstream Magic releases