reserving mega aero

Edit: It's worth noting that Mega Aero is faster than Gengar, meanign that should it get a Roost off when gengar uses the Z-move, it will always live, and won't take enough from Gengar's other attacks.
252 SpA Gengar All-Out Pummeling (190 BP) vs. 0 HP / 0 SpD Aerodactyl-Mega: 216-255 (71.7 - 84.7%) -- guaranteed 2HKO
ah, sorry bout that lol.Gastrodon : Definitely utterly walls gengar so is a great coutner to gengar, but not being able to pursuit trap isn't as nice since there is no punishment as long as gengar doesn't sub up.
AV Scizor: Nice check to gengar, but personally not a fan of the amount it needs the team built around it to support it, ie. wish support etc. Also the risk of them staying in on pursuit and then inducing a 50/50 on the next turn isn't so fun.
Krook: Omg that would totally catch me off guard, didn't even remember that move existed until now. Definitely a cool check though the risk of swapping into a focus blast is always ever present, still one of my favourite choices here. (50/50's would be eventually induced if this became common place, but since it isn't).
Aero: as explained in my post and below, heavily reliant on rocks and fighting-z not ghost. But if you have hippo or no rocks then yea nice check for sure. Also if gengar wasn't chipped and decides to stay in pursuit only has a 43.8% chance of killing, so induces some risk.
Nidoqueen: nice defensive answer, but no pursuit and no recovery means gengar could just chip at it all game, and also stops it from being able to act as a terrakion answer etc after taking hits.
Gligar: Nice counter too, but again like gastrodon no pursuit so no real way of punishing gengar outside of any sub damage, and as below is technically beaten by ghostium gengar. However since this is not the set for the week, I won't count this in my voting, but since ghostium exists its worth noting. (Obviously if ghostium is being factored in I would only class this as a check though).
Worth noting that while the counters that don't have pursuit punish gengar for subbing up, if the enemy does notice these are your only answers and they dont have anything faster than gengar, ie. a scarf hyd, then there is no punishment to gengar for just firing off attacks instad of subbing, and these pursuit-less counters only punishment is via hazards.
Will be voting Krook as check for sure.
Will be voting gastrodon as counter, and because the brief doesn't mention ghostium, probably gligar too, if ghostium is taken into account AV scizor instead, but im not a fan of how restricting it is to build around.
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From Datsplashtho, you forgot that roosting aero loses its flying type and therefore get's obliterated, which means aero only checks gengar if it doesn't substitute, or stealth rocks are down, (and if its ghostium has a good chance to ohko from full no matter what), unless you can bring it in on same turn as gengar comes in.
252 SpA Gengar Never-Ending Nightmare (160 BP) vs. 0 HP / 0 SpD Aerodactyl-Mega: 273-322 (90.6 - 106.9%) -- 43.8% chance to OHKO
252 SpA Gengar All-Out Pummeling (190 BP) vs. 0 HP / 0 SpD Aerodactyl-Mega: 432-510 (143.5 - 169.4%) -- guaranteed OHKO (roosted)
252 SpA Gengar All-Out Pummeling (190 BP) vs. 0 HP / 0 SpD Aerodactyl-Mega in Sand: 290-342 (96.3 - 113.6%) -- 75% chance to OHKO
Note that ofc sandstorm improves this drastically through the x1.5 spD boost, but that is still a 75% chance to ohko if you tried roosting lmao.
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Also wanted to point out that gligar only checks fightinium, not ghostium, as a shadow ball into a ghostium will nearly always kill, but since we are specifically looking at fightinium here I guess it doesn't matter, but is worth noting.
252 SpA Gengar Never-Ending Nightmare (160 BP) vs. 252 HP / 100 SpD Eviolite Gligar: 216-255 (64.6 - 76.3%) -- guaranteed 2HKO
252 SpA Gengar Shadow Ball vs. 252 HP / 100 SpD Eviolite Gligar: 109-129 (32.6 - 38.6%) -- 98% chance to 3HKO
Hey, thanks for replying!Gyro Ba11 By your own calcs, a shadow ball into fighting z does 91.5 - 107.6%, even if you take leftovers into consideration this essentially requires you to be max hp to kill gengar or force it out, (and even then it still has a slim chance to kill you) and swampert has no recovery outside of lefties or potential rest. Not exactly a reliable check.