Heatran

Do you remember when Mega Slowbro had a viability ranking of A- in National Dex? Seems hard to believe that this mon is now completely unranked in the tier. Obviously a lot of this has to do with metagame shifts and Dracovish being banned, but Mega Slowbro is such a unique pick for fat teams that I really wanted to do something with. It's pretty niche unlike its non-evolved form but definitely has its uses. I've been able to adapt an old team from SM OU into the NatDex format and make use of Mega Slowbro without feeling like I'm sacrificing viability by not using a more standard fat pick for my mega slot. I think this is maybe the best team I've built in NatDex and certainly the most consistent when played correctly.

Mega Latias was the initial idea of the build, as I had gotten a bit tired of building fast paced offenses and wanted to try some bulkier stuff, and CM Mega Latias was a Pokemon I always found very fun if you played it right. I chose the Sub + SPower set since with Weavile so popular, feel Substitute forcing Triple Axel alongside a Rocky Helmet Pokemon would be really really fun, alongside potentially Hazard Stack letting me quickly wear down Weavile so Mega Latias could win.

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With the idea ingrained in my head of HStack + Helmet + Sub Mega Latias, I immediately jumped to Ferrothorn since that's a Pokemon which I thought was incredible in the current metagame, and after seeing a lot of Ferrothorn + Mega Latias builds in both NDPL and old SM replays, I was convinced to use it over the obvious other contender in Skarmory. Initially I had used a Rocky Helmet on it to go with my initial idea, but as ill detail later on I eventually swapped it to Leftovers and moved the Helmet to a different Pokemon.

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Clefable was a quick pick for the next slot, it let me slot in Stealth Rocks, a secondary Win Condition, as well as a Dark Resist to help with the likes of Ash Greninja, Weavile, and Hydreigon. I’ve always been a big Clefable advocate, and know how dumb its Calm Mind sets can be, but after playing around with the CM Rocks set for a bit, I realised in meta where Corv is uncommon, and so many Steel types like Mega Scizor, Melmetal, and Heatran so popular, not being able to punish them is horrible. I then decided to make Clefable Rocky Helmet instead as with Clef having actual consistent recovery, it could abuse the Helmet better, as well as opt for Thunder Wave over Stealth Rocks where I got inspiration from a common ORAS Clefable set which seemed demonic.

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Okay, here came the issue of both slotting Stealth Rocks, having some Volcarona and Serperior counterplay, and having a way to pressure Mega Mawile and Ferrothorn comfortably. Heatran was the fairly obvious answer here, and I just opted for a relatively standard SpDef set with Toxic to deal with Volc, and put a timer on Mega Charizard Y, which is a major threat since they are almost always paired with Weavile.

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At this point I realised breaking Toxapex would be annoying since I was SPower MTias, and the likes of CM Tapu Fini, offensive Grounds such as SD Gliscor and Garchomp would be hard to break through. Rotom-W was a choice suggested by a friend, and not something I would think to use on a balance build like this. My skepticism quickly faded as I found out how useful this Pokemon was in battle. Pain Split was a tremendous asset against a lot of teams, and the defensive utility it in itself brought was extremely useful in tight situations.

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Ah yes, I forgot the number one thing all ND teams should have (for the most part). A Ground type. The team also felt quite slow, and with MTias being SubSPower, it meant SD Kartana and the Offensive Grounds were annoying. Scarf Lando T was the clear choice here, filling in all the holes I needed, and completed the team :).