I've been out of the game for a while, and I would like to catch up on what I missed. The biggest question I have is, What's the deal with Moltres being ADV OU now? I remember looking at it once or twice, but Sand ruins Morning Sun and there's no Roost yet, and it's hard to imagine Fire/Flying typing being good when everything is carrying Rock Slide and Tar/Aero/Cune/Mie/Zap being so commonplace. So what does Moltres do exactly? Are there any tour games that really show off what it does?
I'm no ADV expert by any means, but I think having access to a decently fast Will-o-Wisp + its typing has made it a popular pick for a lot of players who are looking for some support against Steels and Celebi. My understanding is that the Fire-type, in general, is not very common in ADV, so Moltres has become the common pick for filling that role since its typing gives it both a Spikes immunity and STAB Fire Blast/Flamethrower, the latter being used to offensively check threats like Metagross, Jirachi, and Heracross (at max speed investment it will always outspeed Metagross and Heracross, assuming no stat boosts are in play) while applying pressure to things like Skarmory and Celebi. I don't think it's meant to be used as a tank like you suggest since its main role is to force out certain offensive threats while inflicting Will-o-Wisp onto incoming Snorlax/Blissey/Suicune/etc. on predicted switch-ins, or Roaring for scouting + Spikes damage. This strategy, in particular, can be rather annoying for a Blissey to deal with, since the combination of Burn + Spikes + Sand forces it to use Softboiled earlier than it might like, opening up opportunities to bring in your own offensive threat that can force Blissey out and preserve your own momentum. If you are able to pull this off effectively, lack of recovery should,
in theory, not be too much of an issue since your goal should be forcing out certain threats, and the Spikes immunity really helps a lot and gives you multiple opportunities to switch in the bird when necessary.
https://replay.pokemonshowdown.com/smogtours-gen3ou-410313
https://replay.pokemonshowdown.com/smogtours-gen3ou-425791
https://replay.pokemonshowdown.com/smogtours-gen3ou-425539
https://replay.pokemonshowdown.com/smogtours-gen3ou-425655
https://replay.pokemonshowdown.com/smogtours-gen3ou-427629
Here are some relevant battles from SPL X. Interestingly enough, only one battle that had a Moltres ended in victory for its user, but I don't think that has anything to do with Moltres itself. As you can see from the replays, Moltres is particularly good at threatening things like Metagross with the Fire STAB or Swampert with HP Grass, while also spreading Burn when it's able to, making it good at shifting the momentum of the battle in the user's favor when given a good matchup. Its also used as a lead in the first battle which I'm guessing is used to immediately threaten Skarmory leads and gain an early lead.
Like I said I'm not too knowledgeable of the ADV metagame so take what I say with a grain of salt. There's probably someone out there who can provide a more detailed explanation, but the Smog analysis doesn't seem to be updated so rip.