Here is the full list of all 12 Switchball trophies - there are 7 bronze, 4 silver and 1 gold.
Collect a Gold Medal on All levels
Complete Lava World
Collect 24 silver medals
Complete Cave World
Find 3 hidden paths
Complete all cooperative levels
Collect 12 silver medals
Complete Ice World
Win 10 matched multiplayer races
Win 5 matched multiplayer races
Complete Sky World level 3
Collect 1 silver medal