What it does
Immunity makes the holder completely immune to Poison and badly poisoned — from moves, abilities, or Toxic Spikes. Total immunity, not a resistance. Nothing gets through.
Why does that matter for Snorlax? Badly poisoned ticks for 1/16 HP turn one, then 2/16, then 3/16 — it snowballs. Snorlax has base Speed 30, meaning it switches slowly and can't run away from a poison clock. Left unchecked, Toxic turns a wall into a timer. Immunity shuts that clock off permanently.
Who runs it
Snorlax (1% usage): Snorlax is Normal type, so Ghost moves already bounce off it. But it has zero natural poison resistance. Immunity fills that gap. The catch: Snorlax has two other abilities — Thick Fat and Gluttony — and Thick Fat is better in almost every game. It halves Fire- and Ice-type damage. Flamethrower and Ice Beam show up in a huge percentage of teams; heavy Toxic stall strategies are much rarer. Gluttony triggers Berries at 50% HP instead of 25%, which suits burst-recovery builds.
Immunity is the right call in exactly one scenario: you read that the opponent is running a dedicated Toxic-pressure strategy. Outside that read, Thick Fat covers more matchups.
How to use it
Immunity Snorlax plays like a straightforward physical wall. You switch it in, absorb hits with its enormous HP (base 160) and solid Special Defense (base 110), and ignore any Toxic the opponent throws. If they're relying on poison to wear it down, they have nothing.
The gap you're accepting: without Thick Fat, Fire and Ice moves hit harder. A Flamethrower that Thick Fat Snorlax could comfortably tank now threatens a 2HKO. Scout the opponent's coverage before switching in — avoid walking into a Fire-type move you can no longer shrug off.
Tips & strategy
When Immunity is worth it: If the opponent has Gengar running Sludge Bomb, a Toxic-passing support core, or Toxic Spikes in play — Immunity earns its slot. Check the team preview for poison-oriented setups before committing to this ability.
What Immunity doesn't cover: Burn, Paralysis, Sleep all work normally. An opponent who pivots to Will-O-Wisp or Thunder Wave still has tools against Snorlax — Immunity only blocks one entry point.
The honest bottom line: 1% usage is the signal. Thick Fat is almost always correct. Save Immunity for the rare team-specific matchup where the opponent has built their strategy around poisoning your wall.