In Ruby & Sapphire, a new feature was introduced called abilities. These were traits that the Pokémon had that could effect things both inside and outside of battle. In Diamond & Pearl, several new abilities have been introduced and below you shall find them:

Adaptibility
 

In-Battle Effect:
If this Pokémon uses an attack that has the same type as it, then the move's power is increased

 

Aftermath
 

In-Battle Effect:
If this Pokémon was fainted by a Physical Attack, the opponent receives damage

 

Anger Point
 

In-Battle Effect:
This Pokémon's attack rises when hit with a Critical Hit

 

Anticipation
 

In-Battle Effect:
Predicts Super Effective Attacks from the Foe

 

Bad Dreams
 

In-Battle Effect:
If the opponent is alseep, it loses health every turn

 

Download
 

In-Battle Effect:
Depending on foe's strongest stat, this Pokémon raises itself in that stat

 

Dry Skin
 

In-Battle Effect:
If Sunny Day is in Effect, this Pokémon's HP Decreases. If Rain Dance is in effect, this Pokémon's HP increases

 

Frisk
 

In-Battle Effect:
Allows you to see your opponent's hold items

 

Filter
 

In-Battle Effect:
If the opponent attacks this Pokémon with an attack that is Super Effective, the attack does half damage

 

Flower Gift
 

In-Battle Effect:
Form Changes when Sunny Day is in effect. Stats are also raised

 

Forewarn
 

In-Battle Effect:
Allows you to see all of your opponent's attacks

 

Gluttony
 

In-Battle Effect:
This Pokémon Uses Held Berries quicker

 

Heat Proof
 

In-Battle Effect:
Fire Attacks used against this Pokémon have their damage lowered

 

Honey Gather
 

In-Battle Effect:
Collects Sweet Honey after battle

 

Hydration
 

In-Battle Effect:
When Rain Dance is in effect, All Status Effects on this Pokémon are Cured

 

Ice Body
 

In-Battle Effect:
This Pokémon's HP Recovers during Hail

 

Iron Fist
 

In-Battle Effect:
This Pokémon's Punching Attacks are increased in power

 

Klutz
 

In-Battle Effect:
This Pokémon cannot use Hold Items

 

Leaf Guard
 

In-Battle Effect:
Any Status Effects on this Pokémon are healed when Sunny Day is in effect

 

Magic Guard
 

In-Battle Effect:
Only attacks that do damage work on this Pokémon

 

Mold Breaker
 

In-Battle Effect:
The Opponent's Ability has no effect

 

Motor Drive
 

In-Battle Effect:
When this Pokémon is hit with an Electric attack, it's speed Increases

 

Multitype
 

In-Battle Effect:
Depending on the Plate attached, this Pokémon's type and form change

 

No Guard
 

In-Battle Effect:
All Attacks while this Pokémon is in Battle have 100% Accuracy

 

Normalize
 

In-Battle Effect:
All this Pokémon's moves are of Normal type

 

Poison Heal
 

In-Battle Effect:
HP Increases when afflicted with a Status Condition

 

Quick Feet
 

In-Battle Effect:
If this Pokémon is inflicted with a Status Condition, its Speed Increases

 

Reckless
 

In-Battle Effect:
All retaliatory moves have increased power

 

Rivalry
 

In-Battle Effect:
If the opponent is of the same Gender as this Pokémon, then this Pokémon's Attack rises

 

Scrappy
 

In-Battle Effect:
Allows this Pokémon to hit Ghost Type Pokémon with Normal & Fighting type moves

 

Simple
 

In-Battle Effect:
Effects from the user's Hold Items and Attacks are increased

 

Skill Link
 

In-Battle Effect:
Raises number of hits when using moves that hit multiple times"

 

Slow Start
 

In-Battle Effect:
This Pokémon's Attack & Speed is halved for the first few turns

 

Sniper
 

In-Battle Effect:
Increases the base value of an attack during critical hit

 

Snow Cloak
 

In-Battle Effect:
This Pokémon's Evasion Rises in a Hailstorm

 

Snow Warning
 

In-Battle Effect:
When this Pokémon is brought into battle, a Snow Storm blasts

 

Solar Power
 

In-Battle Effect:
When Sunny Day is in effect, HP decreases but Special Attack increases

 

Solid Rock
 

In-Battle Effect:
Any Attacks that are Super Effective on this Pokémon have their damage lowered

 

Stall
 

In-Battle Effect:
This Pokémon always moves slower than the foe

 

Steadfast
 

In-Battle Effect:
This Pokémon's speed increases when flinched

 

Storm Drain
 

In-Battle Effect:
All Water Attacks are drawn to this Pokémon

 

Super Luck
 

In-Battle Effect:
Higher Chance of performing a Critical Hit

 

Tangled Feet
 

In-Battle Effect:
Evasion Increases when Confused

 

Technician
 

In-Battle Effect:
The power of this Pokémon's Weaker moves are increased

 

Tinted Lens
 

In-Battle Effect:
After using an ineffective attack, the power of that attack increases

 

Unaware
 

In-Battle Effect:
The foe's stat changes are ignored

 

Unburden
 

In-Battle Effect:
If this Pokémon has no hold item, its speed increases.