What effect did Deoxys-Speed have on the metagame?
Much like its Defense forme, Deoxys-S had access to the two best hazards: Stealth Rock and Spikes. It also had access to the other utility moves that Deoxys-D had, like Taunt and Magic Coat, although it didn't always run them due to having decent offenses and great coverage to beat just about anything. The big impact Deoxys-S made on the metagame that it alongside Defense forme gave hyper offense such a HUGE advantage in the hazard game by pretty much being able to guarantee 2 layers of hazards up, which was ridiculous. So many offensive threats were in the meta at the time, making Deoxys-S a great asset to have on a team. However, another big effect Deoxys-S had was that it could also turn into a huge offensive threat, which is below.
In what main roles was Deoxys-Speed used?
Unlike its Defense forme, Deoxys-S had two roles: hazard setter and offensive cleaner, usually on more hyper offensive teams with other threats in the back. Hazard setter is really obvious, it's just like the Defense forme. However, an offensive set was where it was different. Thanks to its decent offenses and insane speed and coverage, it was a really troublesome threat in the teambuilder, but even more so during actual battles where people had to play mindgames with which coverage moves it was running. It's insane speed stat allowed it to outspeed everything up to
Jolly Scarf Garchomp if you invested fully with a positive nature.
What caused it to have a significant impact?
It's speed stat was the biggest factor. Outspeeding everything was huge and gave teams a great asset against fastmons on opposing teams. Like Deoxys-D, access to a great movepool with offensive and supportive options also helped it a lot to become so centralizing and making HO the best playstyle of the time. Its versatility was absolutely huge as well, it could do every job you gave it incredibly well...hazard setter, cleaner, revenge killer...it did that all. It was so incredibly unpredictable.
How do/did you deal with this Pokemon in OU?
Magic Bounce users, although rare, also could stop Deoxys-S. However, if you lead off believing it was a hazard setter and turned out to be offensive, then it would be a headache guessing its moveset especially because it could still afford to run Rocks or Spikes. Fast taunters didn't work either, so Magic Bounce was the best way to stop it or remove the hazards later on something else. Offensively, priority worked well as it wasn't really bulky, and a team would require a really fast Scarf user like Latios or Keldeo to revenge kill without using priority. Defensively, you'd need a really bulky neutrality to take it on, but even then, Life Orb Psycho Boost would hurt because its power wasn't nerfed to 130 like other similar moves (Draco Meteor, Overheat, and Leaf Storm). There wasn't a whole lot of counterplay to offensive sets except carrying multiple checks and hoping it didn't have the coverage move to blast through them.
