How good do you think a Gastrodon/Virizion core would be? I'm trying to think of something that would work effectively vs Terrakion, Thundarus, and Cress. (I figured if i can get something to counter those three, i can get a trio that would be effective vs most of the VGC threat list.) Gastrodon by itself pretty much fits the mission statement well, being immune to Electric moves, and getting access to moves that are Super Effective vs. Terrakion and Thundarus, getting STAB on the former. Cress can't do too much to it, as it's already slow and just takes neutral from it's main attacks. Against the rest of the meta, it has an amazing defensive typing and has Storm Drain, which means it can save a Fire-Type partner from a Watery Grave (unless Surf/Muddy Water would hit the partner too. Which would then make it a thing to consider when picking a team.)
It does have a 4x weakness to Grass, which brings me to the second choice, Virizion. Virizion is a nice pokemon who also happens to, like Gastrodon, get moves that are Super Effective vs. Terrakion and Thundarus, with STAB vs the former. (which in a way would be kind of significant, due to the fact that it can still kind of do what I intend to do with the core if it's Terrakion/Thundarus and a Grass-type) However Icy Wind will be an issue. Against the rest of the Meta, it gets a nice array of resists and has fairly nice bulk, but Ice is probably very common.
I'm wondering if there would be a better partner than Virizion though. The 'mon I'm looking for would resist grass and preferably do good against Water and work well vs. Terrakion, Thundarus, and Cress. One of the two on the latter part would work, but I feel the former is more valuable due to it being the only type that Gastrodon can't threaten that threatens Fire.
I've also considered Volt Absorb Lanturn, but I'm guessing it's too frail to really threaten Terrakion. It would be a nightmare to Thundarus though.