The problem I see with a set like that is it would have to run Roost along side Heal Bell and Dragon Dance (Assuming thats what you meant by "DDD") which means you would only have 1 attacking move because Altaria would be prone to being weared down without Roost.
Pixilate Return would be its only move which would in turn make it walled by every bulky steel type in the tier. Even if it dropped Roost for Earthquake it would still have problems with mons like Skarmory, M-Scizor, and Ferrothorn. Even after a Dragon Dance its still outpaced by common Scarfers like Lando-t, Protean Greninja, and Jirachi.
DDD Is never used without a trapper such as Magnezone or Alolan Golem, so the argument of Steel types isnt so much of the problem. Steel types like Jirachi and Shed Shell Skarm still pose a problem due to them being much harder to trap.
After seeing the ORAS DDD M.Altaria and Suicune team, I wanted to try the set for myself in SMOU, and tried at first for a Semi Stall build which turned into a Balanced team, but more on that below.
The main problems I found for Altaria is its speed and Poison types. The problems with its speed is that to out speed anything significant, a lot of bulk is given up, or the best way is to give up the speed for Bulk. Only problem is at +2, you can only viable outspeed up to M.Lopunny, leaving Zam and Scarfers all ahead of you, such as Zone, Boom Lando, Lele, Kartana, Gunk Shit Scarf Gren, Excadrill, Jirachi etc etc. At +1 its even more pitiful however, only hitting 304 Speed, letting it being outsped by max Speed LandoT and up.
Toxapex, M.Venusaur and Amoonguss completely shuts down Altaria and can threaten it with both Tspikes and Toxic to waste Heal Bells, powerful Sludge Bombs, or Clear Smog. Not only are these mons annoying for Altaria, they are also really hard to KO for teams in general, with there insane Bulk, access to recovery in Regen and Leech Seed/Synthesis, requiring yet another mon, on top of one for Steel types, to deal with Poison types. The best way is to pair it with a Lure or something that can apply pressure to it, like Gren or Fini, but even these aren't consistent.
I decided to try Z-Extrasensory Gren to lure Pex + Alolan Golem for Steel types. Alolan Golem has a really nice pairing with Altaria, mainly for its ability to trap Heatran, unlike Magnezone.
[Click for Import]
Altaria-Mega @ Altarianite
Ability: Cloud Nine
Happiness: 0
EVs: 248 HP / 56 Def / 188 SpD / 16 Spe
Impish Nature
- Frustration
- Dragon Dance
- Roost
- Heal Bell
I won't go into the building process of the team, but this is the DDD spread I arrived at. 248 HP + 188 SpD allows it to avoid the 2hko from M.Alakazam, 16 Spe allows it to outspeed Ash-Gren at +2, and the rest is put into physical Bulk, allowing it to set up on the likes of M.Lopunny and Scarf LandoT.
I can tell you one key thing, DDD M.Altaria is pretty bad in smOU at the moment. It restricts building too much, and while it has nice defensive typing helping it check Ash-Gren, it lets in way too many threats in for free, and stuggles to provide much Defensive presences outside of checking Ash Gren. With the overall power creep, its 75/110/110 has become surprisingly ineffective for raw walling without resisting, and to add Zmoves on top of that, its quickly over whelmed without full investments.
I may have built around this the wrong way however, as I went with immediate ways to deal with its problems, like Lures and trappers. While the ORAS version does have Magnezone, it has no direct way of dealing with Poison types, only pressuring them slowly with the likes of Suicune. While this is viable in ORAS, I feel Toxapex needs offensive pressure to be beaten during the match, otherwise it will live until the end of the match, both shutting down M.Altaria the whole time in the process, and shutting down any chances at a bulkier team with the required offensive slots.
All in all, DDD M.Altaria feels like a very Match Up fishing pick, and if thats what you want, mons like M.Latias are better for this, as the ability to support them is far easier to implement into teams than M.Altaria. I feel if there any viability to M.Altaria, its in its defog Defensive sets, for fat balances to semi stalls, helping check Ash-Gren and help beat other offensive Hazard setters.
