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I'm concerned about the defensive core as well, I'm not sure Zapdos + Heatran can stand up to a lot of the tiers threats long term. Stuff like Primarina and Enam has no switch-ins
I changed the team so it can tank and had some priority but I don't know if I'm mixing archetypes, I don't quite know the difference between mixing stall and HO and just making a balance team.
The team - https://pokepast.es/16c6a8d216409bed