Are we talking X and Y? It has 2 new forms, one of which changes its type. Its still unclear as to what stat changes or move changes it gets. It could be holding the mewtwonite x or mewtwonite y and your opponent can choose to mega evolve during any point in battle in which it is in play.
(as far as im aware its unclear if it is possible to have mega mewtwo x in pokemon y or vise versa)
If you are talking about defending against super effective spiritomb can already do that
If you are talking about being able to super effect everyone you can't, garchomp can get close apparently but I know electivire or whatever his name is can get 3 less types than garchomp supposedly can. All 18 just isn't gonna happen, even if you got six moves it still wouldn't happen. If you can do it with six let me know that means there is a flaw I. My knowledge I have been trying to fix.
But again, what are you talking about?
Garchomp can get 16 while electivire can get 13
'Check' in pokelanguage means 'to beat in a 1v1' essentially. So I'm asking if there is a Pokemon set that will always Kill mewtwo in a 1v1 no matter what set Mewtwo runs
Oh, well in that case I have no idea, is everything I said right tho? I would love to know if there are 6 move types that if you have all 6 you can be super effective against anything. From what I came up with you need 7 because water is only hurt by elec and grass while normal is only hurt by fighting. Every combination I have come up with has bad one of these 2 types left out and I would love to not have anything left out with only 6 move types.
Ok whoever reported my topic we had a good conversation going on so screw you. A lot of people wrote very good things and now our work is dead. Smooth stuff man
Firstly Mewtwo cannot exceed 394 speed and he has no access to priority attacks so unless there's a Quick Claw involved, there's no way that Mewtwo can out-speed Deoxys (A). First hit Mewtwo with Shadow Ball/Dark Pulse, a decent Mewtwo will survive this and attack back, if not wel you're done. Normally Deoxys (A) won't survive anything but with a Focus Sash it will. And If the first attack was successful Extremespeed will succeed in finishing off Mewtwo.
This always works for me at least in Gen IV and V. So hoping none of the Mega Mewtwo's get a Speed Boost or Priority attack.
(Last part is a lie, I really hope the Mega Mewtwo's will get a Speed Boost)
If we assume that there is no prior damage, switch in damage, and no entry hazards, I believe the closest counter would be Arceus-Bug in rain. (240 def, 12 spd, 252 hp, bold) Judgment is sadly a 62.5% chance of OHKOing, so it's not 100%, but on the other hand, Mewtwo (252+ spa, 252spd, specs) cannot OHKO even with a crit with any attack, except for a crit AND burn on Fire Blast.
So the odds are with Arceus, and I think this is as close as we can get. If Arceus can almost always beat this set, then this Arceus can also beat the other sets with ease with the same terms, maybe modifying the EV spread a bit.
Though, if it includes entry hazards and/or switch in damage, I believe there is no counter.