Deoxys can change its form to adapt and dominant in the Speed, Defense, or Attack stats though it is usually caught with normal stats at first; the stats of the normal form are still extremely unbalanced, as the two Attack stats and the Speed stat are much higher than the Defense or HP stats. Deoxys was given out in the U.S., Japan and Europe as movie event Pokémon, as well as a Gamestop event Pokémon in the U.S. Deoxys can also learn most of the TM moves, making it one of the most powerful Legendary Pokémon to date. It is a versatile, powerful Pokémon, learning a vast variety of moves specializing in all kinds of stats. In the Pokémon anime and manga, Deoxys has the power to regenerate itself. It was the last Pokémon in the Pokédex until Generation IV was released. A glitch will occur if you use a Gameshark to capture Deoxys past the event- when you go to catch it a Missingno will pop up but will have the cry of a Deoxys, as proven in Pokémon Emerald).
The name is derived from the D in DNA (Deoxyribonucleic Acid), to which Deoxys looks like a strand of DNA.
Also because it has an unusual capability to regenarate its damaged parts & also because it can multiply itself like a strand of DNA.
In the Anime
Deoxys appeared in the episode "Cheers On Castaways Island", where it transformed into a stone after struck by a thunderbolt. Near the end, it transformed back into Deoxys and protected Ash, Brock, Dawn, the Corphish and the Mantyke from the meteors that dropped down as it attacked Jessie's Yanmega.
Deoxys appeared in the movie Destiny Deoxys where the purple one tried to free the green egg trapped on the meteorite, however it was attacked by Rayquaza after being mistaken as an intruder for trespassing in its territory. They eventually had a duel somewhere in the arctic where a group of researchers witness the fierce battle between the two, as Deoxys was about to attack, the electrical surge shielded Rayquaza from its vision, giving Rayquaza the opportunity to regain strength, finally Rayquaza manage to defeat Deoxys and fly back into space, while the green egg in the meteorite was brought along by the researchers.
Four years later, the purple Deoxys had fully healed and track down its friend to LaRousse City, it causes a blackout to the entire city and remove all of the city's inhabitants in order to fulfill its search for its friend, however Rayquaza sensed its presence and headed to LaRousse City, Deoxys created a shield around the city, but Rayquaza found a way in and defeated all of the Deoxys clones. Ash and the others were able to provide enough amount of energy to revive the green egg, which hatched into the green Deoxys. The green Deoxys tried to stop the conflict, however the city's security system became haywire and attacked Rayquaza, the two Deoxys helped to defend Rayquaza, however they were overrun by the security robots, luckily Ash was able to deactivate the robot leader using the ID card, Rayquaza now convinced that they weren't intruders flies back to space, the Deoxys bids a farewell to everyone and leaves for space.
Deoxys does not evolve.
Basically like a weaker Attack form, but with slightly higher defenses. Attack form does a much better job, however.
Bold indicates that this Pokémon gets STAB from this move.
In Diamond/Pearl/Platinum, you can change Deoxys' form by going to Veilstone City and pressing 'A' next to the meteorites on the right side of the town. You can do this as many times as you wish. The same can be done in HeartGold/SoulSilver, by taking Deoxys to the meteorites on Route 3, East of Pewter City.
Deoxys is one of the only Pokémon to have nearly identical Pokédex entries in every game in which it appears.
It is one of the strongest Pokémon, having the 504+ of Speed (As Speed Form), Attack, and Special Attack (as Attack Form), and is capable of overwhelming many Pokémon.
When it transforms into another form, they show some changes:
Attack Form: A form that optimizes strength to its fullest.
Speed Form: A form that optimizes speed to its fullest.
Defense Form: A form that optimizes defenses to its fullest.
Normal Form: A standard form that boasts great power and speed, while somewhat retaining balance.
"Who's That Pokémon" entry: "This Pokémon has a brain on its body and can change forms."
Deoxys' speed form was called Flight Form when it was first released.
Deoxys' speed form was not originally intended to be released and was only a last-minute addition for Emerald. This is evident by the fact that its original three forms (Defense, Normal, and Attack) can be put into order so that the first letter of each form can spell out DNA, which Deoxys is based off. But there is also a hint with the Speed Form. The "S" in Speed also refers to the S at the end of Deoxys, because DNA spells out Deoxyribonucleic acid, where the "S" comes after Deoxy.
Although Deoxys was first obtainable in FireRed and LeafGreen, it is the last Pokémon in the Hoenn Pokédex.
Any part of Deoxys which is damaged will regenerate, as seen in the movie.