Battle Moveset

A Good Moveset for Deoxys would have to be this:

Attacks:

Calm Mind
Psychic
Ice Beam
Thunderbolt

Items Attached:

Petaya Berry

Preferred Nature:

Timid

Strategy Using Deoxys

This pokemon is one of the better forms of Deoxys available. A timid nature + 84 EV's in speed Deoxys can outrun every single pokemon there is (without taking into account various speed boosting moves such as agility and pokemon abilities like Speed boost), which allows for the other 168 EVs that would normally go into speed go somewhere else.
With the boost in Special defense from the extra EVs, it should be able to use Calm mind more effectively and survive more special attacks than previously. Fire Punch could replace Thunderbolt or Calm mind. Bare in mind that if you replace Thunderbolt with Fire punch, then you're stuck if your opponent uses a Water/Psychic pokemon.
Though its not like this pokemon will be used much, considering it is a legendary and it is 00ber. An alternative moveset that could be used is the choice banding set, except with the special attack EV's going into Attack instead - Deoxys@Choice band: Brick break, Shadow ball, ExtremeSpeed, HP Rock/Rock slide

EV Corner:

Max out the EVs in Special Attack for Deoxys with 84 in Speed and 174 in Special Defense

Strategy Against Deoxys

The Emerald form of Deoxys, 'Speed Deoxys', is arguably the most well rounded Deoxys of them all. All of its stats are above average (except HP) and no Pokémon can match its speed.
- Outrunning Speed Deoxys is hopeless, so it's better to use a Pokémon with more defences and less speed. It is a pretty safe assumption to say the Special Sweeper is more popular than the physical sweeper due to Calm Mind access and the ability to use it effectively, so a Special Sponge is probably the best way to go about things.
- As for your offence, moves like Shadow Ball, Crunch and Megahorn are you're best bet.
- Alternatively, you could capitalise on the low HP possessed by speed Deoxys and use Night Shade or Seismic Toss to KO it (although it'll take 3-4 hits so make sure you're Pokémon can outlast Speed Deoxys). written by Onimusha

Contest Moveset

A good Contest Moveset for Deoxys would have to be this for the Cool Contest best with Lonely, Adament, Naughty or Brave Nature:

Attacks:

Agility
Swift
Aerial Ace
Hyper Beam

Items Attached:

Red Scarf

Strategy Using Deoxys

If you do the attacks in this following order you should have very few problems; 1st - Agility, 2nd - Swift, 3rd - agility, 4th - Swift/Aerial ace, 5th - Hyperbeam

Locations in Games

Ruby/Sapphire/Emerald Birth Island (Emerald ONLY) Colosseum Not In The Game Fire Red/Leaf Green Not In The Game

Animé Appearences

Deoxys has had an appearence in the 7th movie however this form of Deoxys has yet to appear>