Catch Rate Calculator
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Pokeball Progression
Pokeball progression data is being added for Crystal
Pokeball progression is currently verified for Red & Blue and FireRed & LeafGreen. Other games will be added as we verify mart inventories and pickup locations against authoritative sources.
How to Catch Pokemon
In Crystal, every wild Pokemon has a hidden catch rate value, between 3 and 255. The higher that number, the more likely the Pokeball is to stay closed. Common Pokemon like Hoothoot sit at 255. The roaming legendary beasts (Raikou, Entei, Suicune) sit at 3 alongside Lugia and Ho-Oh, which is why each is a multi-attempt catch.
Generation II keeps the older Gen I catch formula structure, but the ball lineup expands dramatically. Kurt the Apricorn ball maker in Azalea Town introduces seven new situational balls beyond the standard Poke/Great/Ultra/Master, plus the Park Ball you only see during the Bug-Catching Contest. Several Apricorn balls have buggy effects in Gen II (Fast Ball is the most famous case) that get patched in the HGSS remakes. Status is applied as an additive +10 to the catch threshold byte (per the pokegold/pokecrystal ROM at engine/items/item_effects.asm:344-355), which works out to roughly a 2x effective catch boost for Sleep or Freeze — the calculator shows this as a 2x multiplier for clarity, but the underlying ROM math is additive on the threshold, not multiplicative on the catch rate.
How to Increase Your Catch Chance
The same baseline applies as Gen I: there is no False Swipe and no critical capture, so the catch chain is sleep first, chip HP, then throw a situational ball. Gen II just gives you many more ball options once Kurt has crafted you a few.
1Apply Sleep for the catch bonus. Sleep is the strongest status condition for catching in Gen II, giving roughly a 2x effective boost (the ROM applies a +10 to the threshold byte; the calculator displays this as 2x). Four primary sleep moves, ordered by accuracy:
- Power
- —
- Accuracy
- 100%
- PP
- 15
- Power
- —
- Accuracy
- 75%
- PP
- 15
- Power
- —
- Accuracy
- 60%
- PP
- 20
- Power
- —
- Accuracy
- 55%
- PP
- 15
2Chip HP carefully. With the target asleep, peel HP using weak moves until the bar is in the red. There is still no False Swipe in Gen II, so a low-level chip-damage Pokemon and a careful eye on the HP bar are the substitute. Some wild Pokemon hold Berries that auto-restore HP mid-battle (a Gen II addition), which can undo your weakening if you stop watching. If you see the wild Pokemon eat a Berry, peel HP again before throwing.
3Throw the right ball. Gen II expands the lineup well past the original five. Beyond Poke/Great/Ultra/Master/Safari, Kurt in Azalea Town crafts seven Apricorn balls from colored Apricorns you pick off trees:
- Moon Ball (4x intended) on species that evolve via Moon Stone (the Nidoran lines, Clefairy, Jigglypuff). The original Gen II implementation gives no catch boost at all because the code compares against the wrong byte for the Moon Stone item; HGSS rewrites it to behave as intended. Crafted from Yellow Apricorns.
- Love Ball (8x intended) on a wild Pokemon that is the same species and opposite gender as your active battler. The original Gen II implementation has an inverted gender check that boosts on same-gender same-species matchups instead, the opposite of the description; HGSS fixes the inversion. Crafted from Pink Apricorns.
- Fast Ball (4x intended): the original Gen II implementation only triggers on three flee-prone Pokemon (Magnemite, Grimer, Tangela) due to a programming bug. HGSS rewrites it to fire on any species with base Speed 100 or higher. Crafted from White Apricorns.
- Lure Ball (4x intended) on Pokemon hooked from the water with a fishing rod. The original Gen II implementation only gives 3x because the math is coded as add-then-add rather than double-then-add; HGSS fixes the formula. Crafted from Blue Apricorns.
- Heavy Ball (variable) adjusts the catch rate based on the wild Pokemon's weight: heavier Pokemon get a flat catch rate boost, lighter Pokemon take a penalty. Crafted from Black Apricorns.
- Level Ball (variable, up to 8x) scales with the level ratio between your active Pokemon and the wild target. Crafted from Red Apricorns.
- Friend Ball sets the caught Pokemon's friendship to 200 instead of giving a catch bonus. Crafted from Green Apricorns.
- Park Ball appears only during the National Park Bug-Catching Contest, where it temporarily replaces all other balls and is designed to make catching the contest mons reliable.
For non-Apricorn situations, Ultra Ball stays the dependable 2x default. There is no Quick Ball, Dusk Ball, Net Ball, Dive Ball, Repeat Ball, or Timer Ball in Gen II. Those all debut in later generations.
Skipping the Sleep step costs you the same as in Gen I, since there is no critical capture and no stacked-multiplier compensation. With Apricorn balls in hand, the deciding factor for legendary catches is whether you have crafted enough of the right Apricorn type before the encounter.
Crystal keeps the same catch math as Gold and Silver, including the same four buggy Apricorn balls (Fast, Moon, Love, Lure). Crystal locks Suicune behind a fixed-encounter storyline at the Tin Tower instead of leaving it as a roamer. The static Suicune encounter means you can prep with Sleep moves and reset on a missed catch, making it one of the more approachable legendary catches in the game. Raikou and Entei still roam, so the standard advice for those two is to track them with the Pokedex Area mode and have a Sleep user ready to start the encounter.