Snorlax has the second highest CP along all the species in Pokemon Go. This is a guide to get the best Snorlax.
Moves
How strong a move is based on not only power but also damage per second (DPS), gained energy per second (EPS), and required amount of energy (for charge moves).
Lick's DPS is lower than that of Zen Headbutt. However, EPS of Lick is high relative to Zen Headbutt. That means Hyper Beam can be used easily by using Lick.
Snorlax is weak to fighting-type
Snorlax is normal-type Pokemon weak to fighting-type moves represented by Cross Chop. Avoid fighting-type Pokemon like Machamp when challenging gyms.
Snorlax's IV
It is important to Check individual value of Pokemon before powering up an individual. Here are evaluation of IV and link to the guide for IV calculation tool.