What it does
Haban Berry fires automatically when the holder takes super-effective Dragon-type damage, halving that hit, then disappears. It only triggers on super-effective Dragon damage — neutral or resisted Dragon moves leave it untouched.
Put numbers to it: Garchomp eating a Dragon Darts from Dragapult would normally lose around 50–60% HP. With Haban Berry, that collapses to 25–30%, Garchomp survives, and next turn it fires back with Earthquake. Without the berry, it's gone.
Vs. Focus Sash: both let you survive a would-be KO at full HP. The difference is Focus Sash leaves you at 1 HP — one more hit from anything finishes you. Haban Berry leaves you at half-damage health. If you had reasonable bulk to begin with, you might take a second hit.
Who runs it
Every carrier here is a Dragon type, because Dragon-weak-to-Dragon is baked into the typing. Garchomp (10% of sets) is the flagship — it often wants to go head-to-head in Dragon mirrors, and Haban Berry makes that viable. Hydreigon (10%), Noivern (18%), and Goodra (17%) also run it at notable rates; none of them are physical tanks, so that one buffer matters. Altaria (10%), Kommo-o (4%), and Dragapult (2%) pick it up situationally.
The pattern is consistent: Dragons that want to play aggressively in mirrors but lack the physical bulk to simply eat a Dragon move are the ones that reach for this berry.
How to use it
The play is simple: survive the first Dragon hit, then do something with that extra turn. Figure out which turn the opposing Dragon move is coming — if you outspeed and can land your hit first, you might not need the berry at all. If they outspeed you, the berry is your insurance.
In doubles, the berry also pressures the opponent's decision. If they know you carry it, trading resources into you becomes less efficient. If they don't know — and they often don't — they'll commit resources to a KO that doesn't land.
Tips & strategy
Don't waste the survival. After Haban Berry triggers, make sure you have a meaningful action available — a move that puts damage out, a pivot option, something. If you're just going to get hit again next turn, Focus Sash probably served you better since it works against any KO regardless of type.