Field Effects
From Gen III to Gen VIII, if you put a Pokemon with this ability first in your party, you have a 50% chance to force an encounter with a Pokemon sharing the type of all of the Pokemon with this ability
Static
From Gen V onwards, if a Pokémon has an effective speed greater than 1809, it will ignore the effects of this move.
Trick Room
This Pokemon has a niche in RBY OU for its ability to learn Surf through an 1997 event, but a few months later this Pokemon was also able to learn Fly from its pre-evolution getting the move.
Raichu
X: Their beautiful form comes from the muscles they have developed. They run silently in the night.
Liepard
Beak Pokemon
Fearow
If a Pokemon at the front of the party has one of these three abilities, there's a 50% chance the wild Pokemon will be in the upper bound of their encounter level range.
Pressure, Vital Spirit, Hustle
In Generation I, this move divided your crit rate by 4 instead of increasing it like it was intended to. In Gen I and Gen IV, it is affected by Haze.
Focus Energy
In Gen V, this Pokemon was given out to tribute the 2012 VGC World Championship winner, Ray Rizzo
Metagross
Diamond: It has an aggressive nature. It stabs prey with its long, narrow mouth to drain the prey's fluids.
Beautifly
Big Fish Pokemon
Basculegion
After winning a battle, a Pokemon with this ability will have a chance to pick up a specific item. The chance of picking up this item depends on the user's level, starting at 5% from levels 1-10, increasing in increments of 5, ending at 50% from levels 91-100.
Honey Gather
In Gen IV, using this move and then sending out a Pokemon with King's Rock will activate its effect, causing it to be able to make the target flinch.
U-Turn
This Pokemon learns Draco Meteor from events in both Gen IV and Gen V.
Jirachi
Violet: This Pokémon tricks its opponents by playing dead. It is small and weak, but it uses its smarts to survive.
Tatsugiri - Droopy Form
Fertility Pokemon
Landorus
In Gen IV, if a Spinda encounter was forced by this ability, it will have one of 50 patterns.
Cute Charm
In the NetBattle days of Gen III, a programming error led to this move blocking Rapid Spin
Substitute
In Gen I, these two Pokemon could learn Pay Day through a Japanese-exclusive Pokemon Stamp campaign.
Fearow & Rapidash
Shield: The fur on its belly retains heat exceptionally well. People used to make heavy winter clothing from fur shed by this Pokémon.
Diggersby
Tolerant Pokemon
Stoutland
If a Pokémon with this ability is in the first place in the party (even if fainted), the wild Pokémon encounter rate increases by 100%, but it does not effect the Rock Smash encounter rate.
Illuminate
In Gen V, if the player sends out a Pokemon with one of these abilities, the enemy AI will act as though all Pokemon the player sends out after also have the ability unless the on-screen indicator is shown.
Levitate, Water Absorb, Motor Drive, Flash Fire
This Pokemon was able to learn Encore due to the PokePark Egg Event that lasted from March to May 2005.
Cacnea
Diamond & Pearl: By churning its wings, it creates shock waves that inflict critical internal injuries to foes.
Yanmega
Stone Cup Pokemon
Cradily