(not to look boastful, just want to show I’ve just seen a lot on ladder)
Deoxys-Defense also does incredibly well on higher ladder, it leaves higher skilled players only the option to endlessly switch in hopes of deterring pressure.
Deoxys-Defense for b/b+/a-/a
Im user Kosmos-110 and I have a recommendation/nomination for Deoxys-D to a-/a
1.) Deo-D has access to taunt. This coupled with its speed tier grants it the ability to taunt numerous threats such as Tapu Fini, Ferrothorn, Toxapex, Mvenu out of sun, etc. this also grants it the ability to stop setup sweepers such as Mlatias and Reuniclus. (See point #5 for Heatran)
2.) Stoss/Night Shade. Night shade is arguably better here as it allows for no contact damage equal to the users level. This allows Deo-D to provide solid damage to threats as well as prevent recovery with speedy taunts.
3.) massive defensive stats. Deo-d has intense defensive stats. 248 HP investments to deter extra rocks damage grants it near immortality against non super effective attacks. A mere 8 defense investment with bold nature grants it a near 400 defensive stat. This allows for Deo-D to easily set up with cosmic power.
4.)252 Atk Choice Band Weavile Knock Off (97.5 BP) vs. +1 248 HP / 8+ Def Deoxys-Defense: 182-216 (60 - 71.2%) -- guaranteed 2HKO. This may seem scary at first, but once Deo-d recovers after an obvious knock off weavile is left with a much weaker knock off, allowing Deo-D to recover and cosmic power even more.
252 Atk Choice Band Weavile Knock Off vs. +2 248 HP / 8+ Def Deoxys-Defense: 92-110 (30.3 - 36.3%) -- 46.8% chance to 3HKO.
5.) Pressure ability. As mentioned earlier, Deoxys-Defense has access to both taunt and pressure. This allows it to easy swallow up attacks with ease thanks to cosmic power and its massive defense investments. Heatran is an example with this, Magma storm is easily handled with pressure and Heatran is left only to earth power and magma storm after being taunted thanks to Deoxys’ speed tier outspeeding Heatran. This applies to much more than just Heatran, as pressure proves itself to be an asset long term over the course of a match, wearing down multiple Pokémons power points and easily swallowing up z moves as well.
6.) Deoxys-D also does incredibly well against S ranked Pokémon. I.e. Mega Lopunny: in addition to being setup fodder, it can only frustration/u turn on it and take chip damage from rocky helmet. Landorus-Therian: defensive is easily taunted and made setup fodder, Heatran: see point #5
A-/A might be a stretch, however I’ve noticed that it does incredibly well against such a bulk of the Metagame; and I mean such a bulk. I’ve seen it do incredibly well so often I couldn’t possibly see is anywhere below b-. It’s incredibly user friendly and has a very good movepool as well, having access to spikes and teleport.