Most played cards in Zoo:

2 Decks
Arid Mesa
8 copies - 4 average
Knight of the Reliquary
8 copies - 4 average
Misty Rainforest
5 copies - 2.5 average
Bant Charm
4 copies - 2 average
Boom // Bust
4 copies - 2 average
Tarmogoyf
4 copies - 2 average
Scalding Tarn
4 copies - 2 average
Negate
4 copies - 2 average
Ethersworn Canonist
4 copies - 2 average
Meddling Mage
4 copies - 2 average
Loam Lion
4 copies - 2 average
Lightning Bolt
4 copies - 2 average
Kird Ape
4 copies - 2 average
Wild Nacatl
4 copies - 2 average
Valakut, the Molten Pinnacle
4 copies - 2 average
Steppe Lynx
4 copies - 2 average
Path to Exile
4 copies - 2 average
Manamorphose
4 copies - 2 average
Grove of the Burnwillows
4 copies - 2 average
Bloodbraid Elf
4 copies - 2 average