Mewtwo EX is so overhyped.
Yes I said it. I really don't see the appeal of the card, especially depending on the translation. If X Ball does 20x energy attached to both active pokemon, then that's pretty bad, but if bulbapedia's translation is accurate, and it's 20x energy on the defending, well, that's pretty useless. Gardevior can't increase the damage output, and X Ball is probably looking at a maximum of 80 (four energy on an EX with no eviolite), an average of 40/60, and potentially zero damage against cards like Donphan, Yanmega, or a Reshiram that just blue flared and has eviolite attached. None of these are impossible or even terribly unlikely scenarios either.
This brings us to Mewtwo's second attack, which does 120 for (P)(P)(C) and discards one. It's not bad, but it's ultimately a slightly more discard efficient blue flare. In addition, Mewtwo has no acceleration to speak of outside Gardevior, which turns all (P) into (P)(P) on your side of the field. That's all well and good, but a Stage 2, something which has so so consistency as a rule in the first place, that has 110 HP hardly strikes me as a reliable tech. Any dragon, EX or not, can one shot it. Goth can do the same because of weakness (and while I believe it is a bad matchup for Goth, it still bears mentioning), Magnezone can one shot it, and either genie can two shot Mewtwo or Gardevior. Mewtwo EX also gives up two prizes, which is bad for the prize exchange given that Mewtwo really can't OHKO any of the real main attackers without help from pluspower, weakness, or some means of dropping a damage counter. Meanwhile, things that two shot it can get ahead on the prize race, and most of these decks have better recovery.
I know people are saying that Mewtwo EX is doing great in Japan, but these people are overlooking that there are more sets released in Japan that may help Mewtwo or hurt its competition. There's also a good chance that the meta is different there and more Mewtwo friendly, but from what I've seen of the western meta, I can honestly say I don't see much that Mewtwo has to offer that makes it worth the hype, certainly not in its own deck.
Even as tech to counter Gothetelle, without pluspower help, X Ball can't one shot Gothetelle unless it has four energy on it, and any intelligent goth player would probably have such a decked out Gothetelle on the bench to revenge kill Mewtwo EX, as four energy and weakness will barely do it. If someone can tell me why Mewtwo EX is so good, I'm all ears. Maybe I'm missing something, but I'm not seeing what it has over other pokemon in our current meta that warrants two prizes, and I really don't see anything special that if offers over either dragon EX.
Edit: Also, to reply to this:
Dialgachomp
Vilegar
Sablelock
Sabledonk
ZPS
Reshiboar
Steelix
Lostgar
Machamp Stormfront variants.
Machamp Prime Variants.
Magnerock
Regigigas
Palkia Lock
Charizard
Kingdra Variants
Arceus
To be fair, any of the bolded decks were either tier 2 or made obsolete by other decks (namely Sablelock vs Sabledonk) in most situations. Charizard had a weakish damage output for its setup. Arceus was interesting, but took a little time, too much time compared to SPs or Vilegar, and got rolled over by Champ SF. Magnerock didn't see much play, at least where I was. I don't know the whole story behind it, but a fighting heavier meta and slower setup speed were probably important factors. In MD on, Uxie was often enough and Magnetic Draw more or less compensated for Magnezone's energy demanding attack. It was playable, sure, but not in the league of some other decks. There was a definite pecking order as opposed to the rock > paper > scissors matchup we have now.
Both metas have had decent tier two decks, and admittedly, some of the tier two decks last format might have been closer than the tier 1/1.5 than the decks of this format, but the tier 1/1.5s of this format are still more numerous, with decks like Tyram, ZPST, Stage 1 Rush, Reshiboar, ZET, ZEM, Megazone, The Truth, and Gothetelle, Yanmega variants, Mewgar, and Mew box/Mewpluff. One thing that is certainly true, however, is that most of these higher level decks center on only a few pokemon, and just use different combinations of them.
Either way, because the format is so rock paper scissors, I see greater balance of each deck in tournaments, as opposed to the 55/20/5 SP/Champ (or Gyarados)/everything else split.
Getting back to the original topic, what the heck is the "Overpowered Basic Haymaker?" If you mean DnD, I'm pretty sure it's not overpowered, certainly with Eviolite out, and if you really mean the dragons and
Cobalion I have to question how that's overpowered in any way. It has no way to damage the bench, so outrage is looking at a pathetic 40 a turn, maybe 60 if you stack two rainbow, and dropping one rainbow puts any dragon within the magic number before it can attack. That seems about as overpowered as Lostgar was.
I expect, as I have for a while, that Gothetelle will go down in flames upon the release of Next Destiny, but that's it. Tyram and ZPST get a new toy. ZEM variants have another tech to choose from, Vileplume does a dragon swap and may suffer a little due to new legend fragility, and Magnezone gets more popular due to draw and the rare ability to OHKO EXs.