BASIC — Hook: What are you actually calculating here?
Sooner or later in singles you hit this fork: turn one, the opponent leads with a wall you can't break, and you have to choose — switch out now, or click Stealth Rock first? Beginners switch, because switching feels safe right now. Strong players almost always set the rock — because they aren't pricing this turn, they're pricing every switch-in across the opponent's next six Pokémon. This lesson teaches you to run that ledger. Once you can, the fork stops being a guess.
BASIC — Core: the one mental model for hazards
Hold one sentence: hazards don't deal "direct damage" — they lower the effective HP of every Pokémon the opponent owns. They resolve the instant the opponent switches in, they cost you zero offense, and they're pure profit.
Four hazards, just learn the multipliers:
- Stealth Rock: chip scaled to Rock-type effectiveness. Neutral 12.5%, ×2 weak 25%, ×4 weak 50%, ×0.5 resist 6.25%, ×0.25 double-resist 3.1%. One layer only — and the first move to consider on almost any singles team.
- Spikes: grounded only (Flying-types and Levitate are immune). L1 12.5%, L2 16.7%, L3 25%.
- Toxic Spikes: one layer poisons, two layers badly-poisons; a grounded Poison-type switching in absorbs the whole set.
- Sticky Web: grounded switch-in drops Speed by one stage — built to drag fast sweepers down.
The core isn't the numbers. It's: every extra switch the opponent makes is one more free settlement for you.
INTERMEDIATE — Worked → Faded: fold chip into your damage math
Fully worked first. Opponent is Volcarona (Bug/Fire, Rock ×4), full HP. You have rocks up.
- Each switch-in: 12.5% × 4 = 50% HP gone.
- It switches in twice and it's dead. You never clicked an attack.
Now a realistic neutral case. Opponent Dragapult (Dragon/Ghost, Rock ×1 neutral), full at 163 HP (a typical Lv 50 zero-investment bulk line).
- Rocks each switch-in: 163 × 12.5% ≈ 20 HP.
- Your attacker rolls 85–100% in 16 steps and, at full HP, the 1HKO lands on 6 of those 16 rolls (6/16, ~37%).
- After eating rocks once, Dragapult is at ~143 HP. Re-run the same move: now it KOs on 14 of 16 rolls (14/16, ~88%).
- You did nothing extra. The opponent switched once for you, and the KO odds jumped from 37% to 88%.
That's the whole point of hazards: it isn't "20 damage," it's a thumb pressing every later calc onto your side of the scale.
Your turn (faded): opponent is Flutter Mane (Ghost/Fairy, Rock ×1 neutral). You've set rocks + one layer of Spikes. It's grounded, not Flying. Compute: how much total % does it lose on a single switch-in? (Rocks 12.5% + Spikes L1 12.5%.) Then ask: if your attacker is a "3-hits-to-KO" move at full HP, after the opponent is forced to switch in twice, how many hits do you actually need now? Bank that number into your switch decisions.
INTERMEDIATE — When/Decision: race for it, or skip it
Read it as if-X-then-Y:
- If you lead into a wall you can't crack short-term (they're stalling), then set rocks in that window — you lose no offense and now they have to start pricing their own HP.
- If the opponent has two or more frail Rock ×2/×4 sweepers (think Charizard, Volcarona), then treat rocks as priority one — it halves their offensive engine outright.
- If the opponent's whole team is grounded with no Flying and no Levitate, then consider stacking Spikes — at three layers every switch-in starts at 25%.
- If a fast sweeper is sitting above your Speed tier, then use Sticky Web to pull it into range of your priority or a faster teammate.
- If you have no removal and they have a setter, then be careful: don't switch loosely and hand them free settlements.
INTERMEDIATE/ADVANCED — Exceptions: where the simple rule breaks
- Flying / Levitate dodge the grounded trio: Spikes, Toxic Spikes, and Sticky Web do nothing to Flying-types or Levitate mons (e.g. Rotom-Wash) — but Stealth Rock still hits. Rocks don't care if you're grounded.
- Poison-types eat Toxic Spikes: a grounded Poison-type switching in absorbs the entire Toxic Spikes stack and clears it — it sweeps the mine for the other side. Don't lean on it versus Poison.
- Magic Guard: a Pokémon with it (e.g. Clefable) is fully immune to all hazard chip — your attrition ledger reads zero against it.
- Heavy-Duty Boots: the holder ignores all entry hazards. The moment that frail Rock-weak sweeper is in Boots, your rocks do 0 to it. This is the most common "I set hazards, why did nothing happen" reason in singles.
- Air Balloon: gives the holder temporary immunity to the grounded trio (until popped) — but does not block Stealth Rock.
INTERMEDIATE/ADVANCED — Mistake-Autopsy: the classic spin-out
The mistake: turn one the opponent leads a frail thing you could just KO, you think "set rocks first anyway," and they switch out that same turn — your rocks land into a board that's about to get Defog'd off, and you handed them a free offensive turn for nothing.
Why it's wrong: setting hazards is not a reflex first-turn action. Their value depends entirely on (a) how many more times the opponent will switch and (b) whether they carry removal. Against an opponent who won't switch, or whose sweeper is in Heavy-Duty Boots, rocks are roughly a wasted turn.
The fix: before you set, ask one question — how many times will the opponent switch into this rock from here? If the answer is "at least two or three," set it. If they're clearly a one-shot push, don't switch, or run Boots across the board, spend the turn on damage or grabbing the lead instead.
INTERMEDIATE — Predict-then-Reveal: guess before you peek
Q: you have rocks + max Spikes (3 layers) up. The opponent switches in a grounded, non-Flying, Rock-neutral Pokémon at full HP. The instant it lands, how much total % is gone?
…work it out first, then read on.
A: rocks neutral 12.5% + Spikes at 3 layers 25% = 37.5%. It hasn't taken a single attack and it walked onto the field at 62.5% HP. That's why "stack hazards + force switches" is one of the most reliable passive win conditions in singles — you shave a third off the opponent's entire effective HP pool.
ADVANCED — Now-Do-This: audit your real team in the dex
Open the dex at /dex and run your six Pokémon, doing two things:
- Count your own Rock weaknesses: flag every mon that's Rock ×2 / ×4. The ×4 ones (double weak) lose 50% to a single layer of the opponent's rocks on switch-in — those are exactly the frail mons you most want carrying Heavy-Duty Boots.
- Flip it: check the common sweepers you fear: look up the popular fast sweepers your build is built to answer and check whether they're Rock ×2/×4. If they are, your rocks aren't just chip — they cut the opponent's offensive engine in half, which is your hard reason to make rocks priority one.
When you finish you'll have a table: which teammates need Boots, and which opposing mon your rocks wreck. That table is your answer to the turn-one question — race for rocks, or don't — in your next singles game.
Removal (Rapid Spin and Defog) is the next lesson — but the attrition ledger is something to start running on every switch today.