I think the deciding factor between uber and ou is whether he changes the metagame in a positive or negative fashion.
I personally don't like the idea of being forced to run bronzong or jirachi or any of the other deoxys "counters" on a team in order to deal with him. For most teams, they don't have too many problems with deoxys, because most of the OU metagame use these pokemon, for good reasons, and for other reasons besides countering deoxys. With the removal of scarf pokemon, several other "threats" to common pokemon become useless. I use to use scarfed roserade to surprise other teams and hit with a modest STAB leaf storm. Deoxys can't take a leaf storm, but he can certainly revenge kill my roserade, without running a choice item himself, without being locked into a move.
Tangerine has described the metagame in terms of gimmick teams and novelty teams. Gimmick teams are failed novelty teams, and novelty teams are teams built to capitalize on the metagame and surprise common teams with unusual pokemon/movesets. When the metagame has too many failed novelty teams, we can say that the metagame is stagnant. I feel that Deoxys-S has a negative impact on novelty teams because he eliminates the ability for many pokemon with good attacking stats but average speed, such as roserade, from running choice scarves because he simply outclasses them.
I personally don't like the idea of being forced to run bronzong or jirachi or any of the other deoxys "counters" on a team in order to deal with him. For most teams, they don't have too many problems with deoxys, because most of the OU metagame use these pokemon, for good reasons, and for other reasons besides countering deoxys. With the removal of scarf pokemon, several other "threats" to common pokemon become useless. I use to use scarfed roserade to surprise other teams and hit with a modest STAB leaf storm. Deoxys can't take a leaf storm, but he can certainly revenge kill my roserade, without running a choice item himself, without being locked into a move.
Tangerine has described the metagame in terms of gimmick teams and novelty teams. Gimmick teams are failed novelty teams, and novelty teams are teams built to capitalize on the metagame and surprise common teams with unusual pokemon/movesets. When the metagame has too many failed novelty teams, we can say that the metagame is stagnant. I feel that Deoxys-S has a negative impact on novelty teams because he eliminates the ability for many pokemon with good attacking stats but average speed, such as roserade, from running choice scarves because he simply outclasses them.