I'm wondering why people are saying all of the Deoxys forms are deadly...the only one I've seen be even remotely threatening is Deoxys-A, and he can still be checked pretty easily by a lot of non-Fighting weak Steels, which there are plenty of.
Deoxys-D can lay down hazards and do a Cosmic Power set, but honestly, I think there are much better entry hazard layers now, and Cosmic Power is totally fucked over by Toxic Spikes. Nattorei is a prime example of a much better entry hazard layer, because while he may not have Recover, his typing and ability to not be setup bait due to good Attack make him much better for the job. Same thing with Sturdy Skarmory, or Sturdy Forretress. I'm getting the feeling that people are just lumping all of the Deoxys forms together and haven't actually fought many Deoxys-D, because every time I've fought, it hasn't done very much to be honest.
Deoxys-N may have intimidating stats, but it honestly just doesn't hit hard enough. 150/150 attacking stats may be high, but when you're relying mostly on unSTAB moves to do damage, it's just not going to do enough damage. I know that Psycho Boost may be strong, but it does leave Deoxys-N as setup bait for an opponent. Deoxys-N can Calm Mind, but as a glass cannon, he has very little time to set up. As an anti-lead, I haven't found him to be very good, especially with Team Previews making it difficult for him to actually do the job consistently since he could always be met with a bad matchup at the beginning. Just remember, there are plenty of things in the metagame with offensive stats that rival his along with combinations of higher BP STAB and better typing. I honestly don't know how people could think this thing should even be a suspect when Deoxys-A isn't banned. While I don't think Deoxys-A should be banned, if it does get banned, I seriously don't think this guy's going to be following after him if people just try to adapt to the newer threats.
Deoxys-S has served me well as a lead, but I honestly don't think it's suspect anymore. He's received so many nerfs with the new Mischievous Heart users, Espeon and Xatu, as well as the new buffed Magic Coat. Not to mention that with Team Preview, you can pick something that can make its life really difficult as your lead, since I've found that DX-S users pretty much always lead with them no matter what. Dual Screens can be dangerous, of course, but Mischievous Heart users shut this down, and you can also screw up their strategy by phazing them if they're planning to try a Baton Pass chain with the screens. This is easier since Dragon Tail and Overhead Throw exist.