Medal

Medals are achievements that Trainers get for doing several tasks.

Levels
They have 3 different levels with various requirements on how many times a task needs to be performed.

Bonuses
Type medals grants you:

+1 catch bonus for Bronze Medal

+1 catch bonus for Silver Medal (+ 2 catch bonus total)

+ 1 catch bonus for Gold Medal (+ 3 catch bonus total)

This counts only for catching pokemons with type corresponding to the medal. (Dragon tamer medal grants bonus for catching Dragon-type pokemon etc.)