Hidden Abilities - Rangi42/polishedcrystal GitHub Wiki

An individual Pokémon can have a Hidden Ability as in Gen. V+. There are some additional features in this game.

• General encounters have a 5% chance of Hidden Ability. (move_mon.asm)
  • The general ratio is A1 : A2 : HA = 47.5% : 47.5% : 5%.
  • The stat screen now displays the number of Ability with its name: 1, 2, H.
• Those spawning in a Hidden Grotto and hatching from an Odd Egg are guaranteed to have their Hidden Ability. (move_mon.asm, odd_eggs.asm)
• Those from Wonder Trade have a 1/3 chance of Hidden Ability. (wonder_trade.asm)
• The Ability Capsule (Ability Cap) has a new effect: when held by parents on breeding, it now gives a 25% chance, for each parent holding it, that their offspring has the Hidden Ability. (daycare.asm)
  • The female (or non-Ditto) parent now has a 60% chance of passing its Ability down to its offspring after the above Ability-Capsule check, whichever Ability it is.
  • These new features max out the total chance of Hidden-Ability offspring at 81%. (0.25 * 2 + 0.5 * (0.6 + 0.4 * 0.05) = 0.81)
• The Ability Patch is available as a Battle Tower reward.

Note: The modifications onto general encounters and breeding are subject to change due to the Ability Patch's debut.