- With regards to 3-move coverage, how integral is this to typing? Personally, I think we should discuss the coverage type during typing stage; ideally, every typing sub includes potential 3rd coverage types. I'm curious what the community thinks on this matter.
Many brilliant points in the thread about the interplay between the three types (Dragon/Poison/Fire), but I’d like to touch on the 2-move subsets. I had previously opined that a STAB + coverage option should not be so strong that dropping the other STAB becomes a no-brainer (for example, how Kyurem and Great Tusk run Ground + Ice on sets). I have somewhat revised this opinion upon being made aware of the fact of how great Dragon + Fire is in Ubers. Good 2-move coverage enables a lot of defensive and utility sets by preventing easy walling (again, see SubTect Kyurem with Freeze Dry + Earth Power). For sure, on Eternatus sets you miss out on uniquely enabling Poison-type coverage to deal with Fairies, which are normally natively bulky Pokémon like Arceus-Fairy or bulky Pokémon commonly Terastallized into the type, but
that is more a lost bonus than a foundation that is shaken. The foundation itself being strong but not-too-strong seems like a balance to achieve here, especially if we have to make space for limited utility. Won’t go into too much detail here, as I want to have things to say in the Typing stage, but continuing in the same theme of enabling some of the less overt aspects of the mon…
- Regarding Toxic immunity: how vital is this to maintaining the identity of Eternatus? If our typing is not part-Steel or Poison, are we pigeonholed during Ability stage?
I’ll go against the grain of “going against the grain” here

and reemphasize some aspects of this immunity while agreeing that it does not need to be a Poison immunity specifically.
- Poisoning immunity is common on CM/BU setup sweepers
Given that Toxic ramping is one of the few ways to deal with Pokémon that can get out of control via boosts, poisoning immunity is one of the most prized things to have as a slow-setup sweeper. Off the top of my head, Tera Poison/Steel (on stuff like

,

,

), Magic Guard (

) or Magic Bounce (

), Taunt (on BU

), status healing options (Lunar Blessing on

or Jungle Healing on

, which helps with burns too), and just plain ol’ Poison typing (

) are common options to enable these Pokémon to do their job. Even Covert Cloak is relevant here. The caveat here is that Eternatus is explicitly being denied such options, yet it runs unconventional setup like Meteor Beam and Cosmic Power anyway. In fact, some have mentioned that it is one of the Pokémon most likely to execute a second, raw Meteor Beam, as well as one of the few things that can make Cosmic Power without Stored Power work. I believe that the role of the Poison immunity in this is not insignificant, and thus maintaining some sort of resemblance to it through one of our stages (typing/ability/movepool) is pro-concept.
- The number of Pokémon that run Toxic isn’t as important as the few key checks
My line of argument here basically boils down to being commonplace =/= having impact. Yes, Ubers Pokémon run it more, but it is not as if that makes Toxic any less strong on the few things that do run it. It is less likely that you will run into them, but a lot of teambuilding is accounting for not having insta-lose matchups in these unlikely scenarios (take, for example, how building to not lose to Cawmodore is a thing). In fact, flexing into a specific defensive bias (for example, physical on Gliscor/Snaelstrom) and running Toxic as a stopgap measure to common setup demons like Revenankh and Hemogoblin is not uncommon. Conversely, running Tera Poison is also a second-tier counterplay option, after Tera Fire, on these threats as well as stuff like Iron Defense Zamazenta. One might say that the abundance of status-absorbing teammates in the tier might make the immunity less valuable, as you can simply switch to them, but it is important to remember how some of these unconventional sets on Eternatus rely on staying in and accumulating boosts. Thus, switching out does have some cost there, which we shouldn’t ignore. Which runs into this question…
- How defining is Meteor Beam to Eternatus' identity? How about Cosmic Power? Would a Pokemon without any setup feel like Eternatus?
Pretty darn defining for Meteor Beam, quite less for Cosmic Power, although I believe the general line of questioning around unconventional/awkward/limited setup is interesting enough to merit further exploration through other options. I’ve just gone through how some of Eternatus’ traits help it in uniquely enacting these setup modes, and it is helpful to understand the value of other things in its kit through these fixed lenses. Meteor Beam also has an element of being horrible coverage for Dragon/Poison, adding to the tension regarding opportunity cost on Eternatus. But both these moves are more illustrative than prescriptive: we do not have to be limited to them, or even any move for that matter (Berserk, for example, was brought up as unconventional setup), to translate this idea into the OU/CAP metagame.
Also, of course, we need setup and just low enough power to desire it/Life Orb to translate Eternatus.
I guess all of this plays back into the general theme of valuing the defensive, utility, and otherwise unconventional traits of Eternatus. I have asked sources (aka Bumboclaat) and been informed that defensive sets on Eternatus are at an all-time low (but perhaps stable); however, this seems not to have always been the case. I think putting some weight on these sets, which ultimately still possess much less utility than modern giants with all of hazards/Knock Off/pivoting, can lead us to the very interesting question of: why did utility sets work on Eternatus despite its limited ways of using them? Yes, the power of Toxic in Ubers is a factor, maybe the major one, along with Ubers being a low-PP metagame, but this does not exclude its other tools from playing a role. Forcing utility through options like Draco Meteor + Eject Pack pivoting (which also apparently made Eternatus a Knock absorber later?) is a brilliant conceit that deserves some appreciation and perhaps translation.