TDL said:
I'm simply trying to point out here that the entire concept of deprovement is so easy that a monkey could do it.
I don't think you understand the concept of theorcrafting in general. Making something worse doesn't have to be mindless. You can devalue something and make it have a positive effect on the game. Balancing a game is a very fine mechanic that takes a ton of skill. You don't just always make things better, all that does is cause a power-creep, which isn't healthy for the game at all.
Making X-ball only count basic energies, or only energies on him, change the entire usage of Mewtwo and would generally make it better than it is in the areas that it could and would be used. It wouldn't be as splashable anymore, but countering it would be much harder. Changing the energy cost to PC or even PCC for X-ball would make it more understandable, since it forces prism/psychics to be run and not every list can do that. It would also make getting a clutch Mewtwo drop harder, so it would take more planning/skill to play Mewtwo effectively, or at the very least more sparingly.
Dropping its health down to 160 (like people have said) would help, and makes eviolite almost a necessity making it even harder to splash. But you can't just think about the Mewtwo war. 160 is just too easy for Zek/Resh EX to hit, so dropping its health that far really breaks it against the rest of the meta, and bumps it down from maybe a 10/10 to a 6-7/10 or so, since it won't be able to get KOs as easily anymore once it gets up, and it can be countered easier anyways. Since the issue is just the Mewtwo war and its health is balanced against the rest of the meta, making an ability that only effects that part would be a better change then just lowering its health.
It's weakness is also a huge reason that there is an issue with the card, or even a Mewtwo war in general. So if you changed it to Darkness (since that makes sense and Psychic isn't actually weak to itself), you could have more room to play. An extremely basic idea is something like increasing damage done to Mewtwo by other Mewtwo by 40. It would allow its second attack to be used as an effective Mewtwo counter with a PP, or at the very least not make every energy not worth 40 damage with X-Ball, which is just ridiculous.
Also, Psydrive is pretty much never used as is so fixing that while we're at it seems like a good idea. The damage is fine, but a better effect that has more synergy with X-Ball would make it better. Make it discard an energy on the Defending Pokémon would give players options if they can't get an OHKO. It could be pretty annoying against some decks, plus that doesn't hurt its ability to catcher-KO bench sitters like it does now. Also the energy cost of PPC is too high, but PCC seems more reasonable.
With all the nerfs, giving it a RC of 1 and a -20 resistance to fighting would help, but aren't entirely gamebreaking themselves.
IMO,
Mewtwo-EX - Psychic - HP170
Basic Pokémon
Ability: Inner Struggle
As long as Mewtwo-EX is your active Pokémon, all damage done to Mewtwo-EX by your opponent's Mewtwo-EX is increased by 40.
[P][C] X-Ball: Does 20 damage times the amount of Energy attached to this Pokemon and the Defending Pokémon.
[P][C][C] Psydrive: 120 damage. Discard an Energy attached to the Defending Pokémon.
When Pokemon-EX has been Knocked Out, your opponent takes 2 Prize cards.
Weakness: Darkness (x2)
Resistance: Fighting (-20)
Retreat: 1
These changes are pretty drastic, and definitely make the card more of a 8-9/10 than the 10-11/10 it is now, but it has strong attacks, a good health and still has a decent counter in itself, although constant revenge KOs are harder to string which can prevent every other game from boiling down to the Mewtwo exchange.
ps im not good at tcg theorycrafting.