Gym Badges
With the new gym System that has come to Pokemon GO, the Motivation System as it is so being called, the idea of Gym Leaders has been done away with. In the previous Gym System, the Prestige System, the player who left the highest powered Pokemon at a Gym would be crowned the Gym Leader. Now, however, since the Pokemon at a Gym are battled in the order they were placed, Gym Leaders no longer exist.
To replace this idea, niantic made sure to include the concept of gym Badges within the Motivation Gym System. Each and every time a player would spin the PokeStop or place a Pokemon at a Gym not previously claimed, they will obtain the Gym Badge for that given Pokemon Gym. There are four different Levels of Gym Badges: Standard, Bronze, Silver and Gold. As you rise in these rankings at a Gym - done by defeating opposing teams at the Gym, the length of defending the Gym for your team, and the number of berries you feed to your defending Pokemon - you will receive an addition item for each stage from the Gym's PokeStop.