Mew2 vs Machamp
Which will perform better as a fighting type attacker like, a focus Blast mew2 or a C DP Machamp, and of Machamp, why do people like FB on a mew2
Answers
As a pure fighting type, Machamp does the job a little better. One of the two main jobs for fighting types is defeating dark types, and Mewtwo doesn't do a great job of that. Against Tyranitar, FB Mewtwo is worse than double fighting Poliwrath or Ursaring.
As to why people like FB Mewtwo, it is a great gym clearer, and fun to use. It hits very hard like a glass cannon, but has the bulk of a Dragonite.
I have two Mewtwos, a PC/FB (L31, 10/10/10, CP 3331) and a C/SB . The PC/FB is for gyms, and the C/SB is for raids. C/SB Mewtwo is great against Machamp, Alakazam and Gengar raid bosses, where dodging is at a minimum, and time is limited. But for gym battles, when you have all the time you want, and can dodge more to conserve potions, PC/FB Mewtwo melts the most important gym defenders, and does an adequate job against almost everything else. It will even handle a half-demotivated Tyranitar without any trouble.
And focus blast has a great animation.
I've found that the consensus around where I live is to shoot for a Shadow Ball Mewtwo and a Focus Blast Mewtwo. You really don't need a team of Shadow Ball Mewtwos for anything except pre-groudon Raikou raids, Focus Blast Mewtwo, and later legendary raids such as Latios. Focus Blast Mewtwo is only good for gyms, being a merely decent fighting counter and generalist for raid bosses. For gyms, it is very potion efficient and carries good typing.
In fact, a lot of people here go for a Focus Blast Mewtwo first. I personally don't understand this decision but with revives so rare I can't blame them.