I was one of the many people who got to play as Mewtwo in Smash 4 on the 15th. Having only vague memories of trying him in Melee and sucking in the ensuing matches, I was cautiously hopeful that I'd find him more acessible this time around.
Suffice to say that I look forward to using him on my next Smash Tuesday. :)
I don't really remember enough about Melee Mewtwo to discuss the differences (and I am NOT going through the playtime needed to unlock him on my own save file), so I'll just go over some of his moves and what I liked. Hopefully this will tide over any folks who are waiting to purchase him on April 28th.
As one would expect, Mewtwo's all about psychic-based attacks and movement, but his standard attacks mix in physical strikes, focusing on his tail. On the ground, his neutral standard, a quick psychic "punch", does 4% of damage, while his side standard is a swipe of his tail, doing anywhere from 9% to 15%. Mewtwo varies his physical and psychic attacks a fair bit while in the air. Smash attacks are more psychic-based, and they hit pretty hard, with great launching power.
Mewtwo's specials include Teleport (up), Confusion (side), Disable (down), and Shadow Ball (neutral). Teleport is familiar to many Smash players who use the likes of, say, Palutena, but Mewtwo's executes quickly, and he floats for a second if his warp destination is in the air. It's handy for sudden changes of target or tactics. Confusion flips around the target a bit, but it's very short range. Disable will stun an opponent - the more damage, the longer it lasts - but it only works while making eye contact. It's perfect for setting up a battered opponent for a KO. Shadow Ball is a charge move that doesn't auto-fire when fully charged; at any point while charging, you can hit the shield button to store the charge and resume later.
He isn't without drawbacks, of course - Mewtwo has a light body and is quite easy to launch. He's a high-risk yet high-reward character, as a result, so make sure you're skilled with shielding and rolling!
I'm having a blast experimenting with Mewtwo, and although I can't defeat high-level CPUs yet, I don't think it will take long.
I'm willing to bet that players can fight with/against Mewtwo online regardless of purchase status. The download for Mewtwo himself, according to the eShop, is 58 KB on the Wii U and 16 KB (two blocks) on the 3DS. That's impossibly small - and leads me to believe that Mewtwo's data is actually in the 1.0.6 update, ensuring that everyone playing online has Mewtwo's code on their system.
I wonder if Nintendo will use this method for future DLC (meaning game updates when new characters come out), or if it's just for Mewtwo. Unlike Mario Kart 8's DLC tracks, characters probably don't use much disk space, so it's not that unreasonable to push DLC data onto everyone's console. (The biggest caveat, in my opinion, is that each update could break replays, meaning that replays you made the day of Mewtwo's release could be unplayable in two months when Lucas comes out. But then again, that really should only happen when the game balance is tweaked ...)
Anyway, hope to see you fellow Mewtwo fans online!