Best poc to attack snorlax

I think you have to use Pokemons with high durability and stamina.
Dragonite-vaporeon-Arcanine-Exxegutor.
Lapras
With all of these pokemon with a decent CP and Dodging you could take down 2 or 3 snorlax with everyone if there is 2 or more people fighting.
if you are asking about fight alone, i think it could be a waste of potion and time.

My favorite is Vap. Try your best ones and you'll feel comfortable with one. I like Vap because it's fast with water gun and dodge. Maybe it's just me but Lapras and Exeggutor feel sluggish while dodging. As a bonus, Vaps are easy to come by, so you can have an army of them.

Machamp with Karate Chop/Cross Chop (or Submission) should be the best poc to counter Snorlax.

Dragonite with db. With proper dodging, you will need 2 or 3 of them to kill all Snorlaxes.

Answered millions of times here.

What others said is right except the guy who said Machamp wich is a crap.
Also I like Pidgeot a lot for Snorlax
A 1600 pidgeot can kill 2x 2000 Snorlax minimum easily. If Snorlax has lick you don´t have to waste time dodging except for the charging attacks

I like using either my Blastoise or Poliwrath with quick moves like mud shot/bite/water gun and hydropump. Fortunately most of the Snoralax's have lick and earthquake/hyper beam which are honestly easy to beat. These water mons are also a bit tanky which I think is absolutely necessary to absorb lick attacks. For the sake of saving time I usually only dodge charge moves. Hydro pump is important as it really does the majority of the damage.
Honestly the best thing to do is to find a friend to take the gym down with you. 2 players on a gym simultaneously is more than 2x faster than one player by themself. You will get more XP and save potions fighting in groups as well. Strike a conversation with somebody playing at your local lure hot spot and make a poke gym date.