I'm bored so...
Luxray
HeartGold/SoulSilver, Y: Luxray's ability to see through objects comes in handy when it's scouting for danger.
Ignores evasion modifiers, Substitute and Illusion.
Pearl, X: When its eyes gleam gold, it can spot hiding prey--even those taking shelter behind a wall.
Ignores Light Screen, Reflect, Safeguard, Protect, Detect, Mat Block and Crafty Shield.
Weavile
Black/White: Evolution made it even more devious. It communicates by clawing signs in boulders.
Y: It lives in snowy regions. It carves patterns in trees with its claws as a signal to others.
Every claw, slash and scratch based attack has a 50% confusion rate against rock types and trevenant. If the opponent is confused, fury swipes will be used every turn on top of Weavile's normal attacks until it switches out.
Lumineon
Platinum, Black/White, Black/White 2: It crawls along the seafloor using its long front fins like legs. It competes for food with Lanturn.
> Takes 25% struggle damage every turn if the opponent has a Lanturn. The same happens to the opponent's Lanturn.
Pearl: To avoid detection by predators, it crawls along the seafloor using the two fins on its chest.
Evasion boost (+2?) if the opponent is carrying a super-effective move. If this happens, -1 Attack as Lumineon is intimidated.
X: It lives on the deep-sea floor. It attracts prey by flashing the patterns on its four tail fins.
Opponents lose an evasion stage every time Lumineon attacks.
Rhyperior
Diamond/Pearl: It puts rocks in holes in its palms and uses its muscles to shoot them. Geodude are shot at rare times.
10% chance for the opponent to be hit by Head Smash from base 80 attack after using a rock type attack.
HeartGold/SoulSilver: From holes in its palms, it fires out Geodude. Its carapace can withstand volcanic eruptions.
Immune to fire-type moves.
Tangrowth
HeartGold: When it remains still, it appears to be a large shrub. Unsuspecting prey that wander near get ensnared by its vines.
Opponent gets ingrained upon making contact
Y: Its vines grow so profusely that, in the warm season, you can't even see its eyes.
Regenerator heals 50% instead of 33% in the sun.
Leafeon
Diamond/Pearl, Y: Just like a plant, it uses photosynthesis. As a result, it is always enveloped in clean air.
Leafeon has a permanent safeguard effect.
Black/White: It basically does not fight. With cells similar to those of plants, it can perform photosynthesis.
Leafeon can only use status moves.
Gallade
HeartGold/SoulSilver, X: Because it can sense what its foe is thinking, its attacks burst out first, fast, and fierce.
Gallade attacks before the opponent.
Platinum: When protecting someone, it extends its elbows as if they were swords and fights savagely.
+2 attack if you switch Gallade in from a pokemon in the Human-Like egg group into an attacking move.
Regigigas
Diamond/Pearl: There is an enduring legend that states this Pokémon towed continents with ropes.
Regigigas gets Huge Power on top of Slow Start.
Regigigas gets Superpower.
Giratina
Platinum, Black/White, Black/White 2: It was banished for its violence. It silently gazed upon the old world from the Distortion World.
Mean Look is constantly active on the opponents side. However, Giratina is considered to be fainted at all times.
Alternatively, you can use the pursuit effect on any attack. Giratina is still considered to be fainted.