Secret Power

Deals damage and has a 30% chance to inflict a status effect which depends upon the terrain.

Secret Power deals damage and causes a variety of different secondary effects depending on the current terrain.
Secret Power also changes its own animation to another move depending on the terrain.
The list of secondary effects of Secret Power varies highly by generation:

Gen 3

Terrain	Secondary Effect	Move Animation
Building and link battle	paralysis	Strength
Plain terrain	paralysis	Slam
Sand	lowers accuracy by one stage.	Mud Shot
Cave	flinching	Bite
Rock	confusion	Rock Throw
Tall grass	poison	Needle Arm
Long grass	sleep	Magical Leaf
Pond water	lowers Speed by one stage.	Bubble Beam
Sea water	lowers Attack by one stage.	Surf
Underwater	lowers Defense by one stage.	Waterfall

Pokémon Colosseum and Pokémon XD

Terrain	Secondary Effect	Move Animation
Buildings, The Under Subway, Realgam Colosseum Mt. Battle (Areas 1-3), S.S. Libra	paralysis	Needle Arm
Outskirt Stand, Phenac City, Cipher Lab (outside)	lowers accuracy by one stage.	Needle Arm
Pyrite Town, The Under, Cipher Key Lair (outside), Citadark Isle (outside), Rock Poké Spot, Pyrite Colosseum, Mt. Battle (Areas 7-10)	confusion	Needle Arm
Phenac Stadium	lowers Defense by one stage.	Needle Arm
Agate Village, Relic Stone, Mt. Battle (outside), Pokémon HQ Lab, Kaminko's House, Mt. Battle (Areas 1-3)	poison	Needle Arm
Relic Stone	sleep	Needle Arm
Pyrite Cave, Relic Cave, Deep Colosseum, Mt. Battle (Areas 4-6), Cave Poké Spot	flinching	Needle Arm
Gateon Port	lowers Attack by one stage.	Needle Arm
Oasis Poké Spot	lowers Speed by one stage.	Needle Arm

Gen 4

Terrain	Secondary Effect	Move Animation
Building and link battle	paralysis	Body Slam
Distortion World	paralysis	Pound
Sand, plain terrain and puddles	lowers accuracy by one stage.	Mud Slap
Cave and rock	flinching	Rock Throw
Grass	sleep	Needle Arm
Water	lowers Attack by one stage.	Water Pulse
Snow	freeze	Avalanche
Ice	freeze	Ice Shard
Marsh	lowers Speed by one stage.	Mud Shot

Pokémon Battle Revolution

Colosseum	Secondary Effect
Lagoon	paralysis
Main Street	paralysis
Neon	paralysis
Courtyard	paralysis
Gateway	lowers Attack by one stage.
Waterfall	sleep
Sunny Park	sleep
Crystal	lowers accuracy by one stage.
Magma	lowers accuracy by one stage.
Stargazer	lowers accuracy by one stage.
Sunset	lowers accuracy by one stage.

Gen 5

Terrain	Secondary Effect	Move Animation
Building and urban	paralysis	Body Slam
Sand, plain terrain, rock and link battle	lowers accuracy by one stage.	Mud Slap
Cave	flinching	Rock Throw
Grass	sleep	Needle Arm
Water	lowers Attack by one stage.	Water Pulse
Puddles	lowers Speed by one stage.	Mud Shot
Snow	freeze	Avalanche
Ice	freeze	Ice Shard

Gen 6

Terrain	Secondary Effect	Move Animation
Building, plain terrain, Sky Battles, and link battles	paralysis	Body Slam
On Electric Terrain	paralysis	Thunder Shock
Sand and rock	lowers accuracy by one stage.	Mud Slap
Cave	flinching	Rock Throw
Burial ground	flinching	Shadow Sneak
Space	flinching	Swift
Water and underwater	lowers Attack by one stage.	Water Pulse
Swamp water and marsh	lowers Speed by one stage.	Mud Shot
Soaring in the sky and Sky Pillar	lowers Speed by one stage.	Gust
Snow	freeze	Avalanche
Ice	freeze	Ice Shard
Volcano	burn	Incinerate
Grass, Grassy Terrain, and Coumarine Gym	sleep	Needle Arm
On Misty Terrain	lowers Special Attack by one stage.	Fairy Wind

Gen 7

Terrain	Secondary Effect	Move Animation
Building, plain terrain, Sky Battles, and link battles	paralysis	Spit Up
On Electric Terrain	paralysis	Thunder Shock
Cave	flinching	Rock Throw
Sand, dirt and rock	lowers accuracy by one stage.	Mud Slap
Water	lowers Attack by one stage.	Water Pulse
Snow and ice	freeze	Ice Shard
Volcano	burn	Incinerate
Ultra Space	lowers Defense by one stage.	Psywave
Grass, field, flowers, and on Grassy Terrain	sleep	Needle Arm
On Misty Terrain	lowers Special Attack by one stage.	Fairy Wind
On Psychic Terrain	lowers Speed by one stage.	Confusion

• In Gen 3-4 Secret Power's power is doubled by Serene Grace
• In Gen 3 and OmegaRubyAlphaSapphire Secret Power can be used out of combat to create a Secret Base
• From Gen 8 onwards this move can not be selected in battle.