So I went ahead and built/tested the Gastrodon
@ Covert Cloak
Adamant 252 HP / 56 ATK / 200 DEF (I eye-balled it without calc'ing, feel free to propose better!)
Tera Type: Water (NOT Ground, reasons below)
Using this set, I have been really happy with it though it's certainly not a silver bullet and I want to share the strengths/weaknesses and other things I've learned using it.
(subtracting about ~4 practice rounds where I lost while figuring out how to play this the most optimally in actual battle):
In Online Raids: 6/6
In Solo Raids: 6/8
The Strengths of the Set:
Greninja basically can't break this at all. It's an immovable fortress in both online and solo. If there was unlimited time, Gastrodon would inevitably win no matter what (the challenge is getting it to win in time..). Compared to Vaporeon or Slowbro, it feels extremely reliable because you're basically never in a situation without answers to hax, never praying to hit or not get crit. You always are at enough health to priority cheer or recover yourself back in, you're always able to clear double teams, you're never worried about Freeze or Poison. Also relevant, you're bringing Terastelize online very, very early, and not worrying about even hitting Greninja to get the Tera charges you need to break shield. Once you get used to using it, your next best play is usually pretty clear, and you're progressing without break. Also as a note that other Gastrodon players probably already know, Greninja uses all 4 of its attacks against Gastrodon (including Hydro Pump thankfully!), so you must be ready for all 4, but also means you get really free turns every time it Pumps or even Gunk Shots.
You have answers for everything Greninja has-- typing/bulk boosting to make yourself invincible, enough so that you can absorb Crits pretty comfortably, clear smog for double team, immunity to freeze/poison, and a way to boost your power + super effective stab--> It's kind of a "bring a whole raid team in one mon" with the only issue being enough time to do it all.
Gastrodon feels almost invincible with reasonable partners. Because I thought this up for solo raids post event, I thought it would be a Jack of all trades, king of none, and be sub-optimal for Team Raids, but turns out the flexibility means it does any job well enough to build a winning team with most common teammates. Depending on what others load up, I can play this full support or full sweeper, or just contribute to both.
With 3 Bro/Vaporeon:
Sure this Gastrodon is not a perfect support missing out on things like Chilling Water, Thunder Wave, Intimidate, Acid Spray other supporters have-- but loaded up with 3 Stored Power sweepers, it does a good enough job of support with smartly prioritizing Defensive/Health cheers to bring the Bros online, and then clearing double teams to make sure they hit their mark and bring Greninja down in time.
With only 1 Bro/Vaporeon, 2 other supporters:
This is super easy to win, and even with just 1 Stored Power user Gastrodon bring enough muscle, aggression, chip damage to raise the overall team's offensive ability to easily bring Ninja down. Feels impossible to lose this.
With 3 support mons:
Really, really rare... people usually biased to bringing bros because of leftover mons from Cinderace Raid, but I did get 1 raid of the 6 where I was teamed up with Clodsire, Miraidon, and Qwilfish. It wasn't ideal, it was a bigger struggle than any of my other 5 raids, but the team saw Gastrodon Cursing and they forewent on Acid Spraying to instead Offensive Cheer and Helping Hand to get Gastrodon boosted until it snow-balled and killed Greninja.
, the issue is always time. Gastrodon really needs to get to +5 or +6 to finish off Greninja, and ideally with an offensive cheer on top of it. Fortunately, because of Intimidates/Defensive cheer by the NPCs, Gastrodon comes online easily and as mentioned above, is always making progress start to finish. Gastrodon grabs chip, powers up, and eventually brings Greninja down without falter. Its offensive capability is the major issue, but overall it still feels to me more reliable than Vaporeon/Bro, it'd take more testing to see if that actually pans out in data.
The Weaknesses of the Set:
Power in Solo Raids. Mentioned a few times but Gastrodon's missing on power even Terrastelized at +4, really want to get to +5 or +6 when solo raiding.
I also tried using Tera Ground (saving up shards all last week!) and that DEFINITELY solves the power issue. The only problem is that Ice Beam stings waaayy too hard post-Tera. Especially when Greninja starts double-attacking late game-- getting hit by 2 Ice Beams without time to answer and the very real chance one of them Crits... note: Tera Water does remove your Gunk Shot resistance, but between your natural bulk, +5 defense/other modifiers in play, and saved up cheers because of how self-reliant Gastrodon is, late Game Gunk Shot isn't really a threat.
With the Ice Beam Tera Ground Gastrodon felt too unreliable to me, playing kind of akin to Bro or Vaporeon where you have enough power that you feel you can get it pushed through, but you're squeezing your skirt that you hope you don't get crit. At least you have the option of Clear Smog'ing over those mons, but when you're having Ice Beams raining down as the clock ticks, the choice to take a turn Clear Smoging is tough.
Maybe someone can find an EV spread with enough Special Bulk to ameliorate these issue, but it does come at the cost of something. I'd say that the current spread feels so reliable in taking hits that maybe a bit of that physical bulk could be swapped for Power or Special bulk.
Finally, in solo raids a real annoyance is having to soft reset if you ever get Arboliva
. Arboliva is always getting hit and you play in a constant state of Grassy Terrain up, but that basically makes it impossible for Gastrodon to win with Earthquake. Overall though, found re-setting the raid for a non-Arboliva team to be not that bad.
How to Use:
Turn 1: Curse
Turn 2: Clear Smog (Tera charge 1)
Turn 3+: Earthquake (Grab chip, Tera charge 2+) Note: In both solo and team raid, you're always going to be fine defensively just at +1 after considering Intimidates/Chilling Waters/Defense boosts others will be using so no point in boosting past +1 until after the shield goes up.
(After Boosts Get Clears)
Curse once, then if Shield has not gone up yet somehow, keep Earthquaking for chip/tera boosts. Going straight for Curse Stacking works too.
(Shield goes up)
Curse until you get to +5 or +6, using Recover or Heal Cheer smartly to stay in the game.
Don't Terastelize until you're about to start attacking to keep your Gunk Shot resistance, though I've never been seriously hurt by Gunk Shot even after Tera.
Power boost with Cheer
Then Terastelize and start Earthquaking for the win.
Use Clear Smog only when there are 2+ Double Teams stacked. Trying to clear every +1 evasion is impossible from my experience.
This Gastrodon is an awesome general use set for folks without friends to organize with. It pairs up surprisingly well with most meta teams even if attacking on the physical side instead of special for reliable online raid wins, and is a notable option for solo raids. Please give it a try!