This is more a question of playing the game rather than Deoxys itself. Impossible to gain momentum? You can't just win that easily by throwing screens up. Common scenario: Haxorus or Nite gets in on turn 4, sets up on turn 5, weakens / KOs counter on turn 6, (depending on the counter this can last until screens are gone or just if they sac a mon to weaken it and stall screens, then hax is revenge killed by steel or scarfer. Deo is gone, a sweeper is gone, one mon killed, momentum gained against scarfer. I don't see how that is uber...especially when you have things that are capable of revenging every sweeper available. The next sweeper is brought it, just switch out to something that can limit it from setting up, then bring the revenge killer back. Most sweepers will lose to scarfers bar agility boosts, most of which are weak to priority or bulky mons. It's fair game. 2 screens or 1 screen and stealth rock is simply not uber. Uxie can do that, so can azelf, almost as many times as Deoxys.
I've already stated several efficient and common ways of dealing with it. Besides saying that they aren't, care to explain?
It seems logical to me that you don't find Deoxys-S broken when you can't recognize his importance at HO teams.
You even believe that if Deoxys-S wasn't around another screenr would just take its place,while this is so obviosuly wrong.
So while i get why you don't find him broken(you don't get his importance as a screener combined with his other very good sets and versatility)
you cannot say anymore that reasons have not been given to you to explain you Deoxys-S brokeness.You just don't get them or don't agree with them.
Finally you can always go and ask a HO offensive player to talk to you about Deoxys-S.Not about his brokeness,because this is arguable,but about the difference between him and other screeners...
um. haxorus, while it will be able to get to +2/+2 can still be beaten by stuff like gyro ball ferrothorn. even if it does get up to +2/+2, it still can't ohko most steels with Outrage, so it will eventually be revenged.
and espeon is probably as good as deo-s, tbh (though the inability to outspeed scarfers is "meh").
Haxorus can even use Dragon Claw if it is at +2,and kill almost everything while not getting locked.So when your Ferro comes in it will simply get ohkoed by Brick Break.
Anyway i am going to repeat the reasons that,imo,make Deoxys-S broken.
1.His DS screen is his best set and the one i find to be broken.It offers immense support WHILE at the same time can setup both entry hazards.No other screener comes even close on doing what Deoxys-S does for offensive teams.
2.His hazards setter set is just a little bit less threatening but very dangerous as well.Again this set helps greatly offensive team with the entry hazards it sets helping sweepers to sweep.
Deoxys-S as a hazard layer will MOST of the time get 2 layer of entry hazrads up which is all an offensive team needs to break through walls and counters.Also Deoxys-S holds a great deal of unpredictability which allows him to ohko common spinners or counters(TTar,Starmie,Tentacruel etc).This makes the opponent more conservative when facing Deoxys-S,forcing more switches and thus giving more free turns for Deoxys-S to lay hazards.
Finally even after Deoxys-S dies the hazards that he put are not easy to get rid of since offensive teams don't leave you too much space to react.
3.When taking the LO cleaner,which is a very good set but not broken like the other 2 sets,into account you find that Deoxys-S runs 3 very good sets,each of them having different counters and each of them being very destructive and dangerous.
So even if the hazard layer set or the DS set weren't broken on their own,if you combine them alltogether they create a broken result.
Finally to also cleat this up i want everyone on the pro-OU side to tell me some counters or ways to reliably beat the DS set,which means giving to Deoxys-S only 1 turn of setup.