Mewtwo IVS
How much different would a mewtwo with 14A 15D 14HP perform than mewtwo with 15A 13D 12HP and a mewtwo with 15A 15D 10HP?
Answers
There will be a about a 1% difference in about 2% of fights...the rest of the time they will operate identically as long as they are powered equally.
In some specific circumstance you may hit att or def break points on one that a different IV doesn't...but the instance will be rare, and the difference will be minuscule.
Basically...they will all operate the same (as long as movesets and level are consistent)
...if they have different move sets then that is a whole other thing.
A level 30 Mewtwo with 15/15/15 will have CP 3413. Same Mewtwo with 10/10/10 will have 3275, so the difference in CP is 138, which is about 4%. In practice, the individual changes matter some, but all of this can be overcome with leveling up. Level the 10/10/10 Mewtwo to level 32.5, and it will have CP 3413, exactly the same as the 100% one.
The cost to get there is a little higher, and/or the ceiling is a little lower. Bottom line, power up the most powerful Mewtwo you have and use it appropriately. You got what you got, now make use of it.
If there were a source for lots and lots of Mewtwos, then you would consider holding out for a better one. But the opportunity cost of not using the one you have is very large, and if you get a better one later, power that up too.