It was a nice match. Some things you can improve on:
You use the down tilt far too much. Now don't get me wrong, the dtilt is one of the best combo starters, but if the enemy sees you using it that much, he is going to think that it is your only way of initiating an attack and will as a result predict that that is all you will be doing. When an enemy predicts your movements correctly, you will find that your movements are less effective.
Work on improving the number of approach techniques you have. An approach combined with shadow ball spam throws off a huge number of players. Also, baiting your enemy into attacking works extremely well. Improve your wave dash control to the point where you can be within an enemy's forward smash range, wave dash out as he activates it, then wave dash or dash forward and attack/grab him in the lag of the move.
Do not fear Fox's reflector. In fact, it can be a serious downfall for them depending on the player. Most Foxes that play against a Mewtwo will think that their shine will protect them perfectly from all of your projectiles. They will become so secure with this that they will be over eager to send your projectiles back to you. Use this to your advantage. A lot of times, when a Fox shines something back to you, they do not jump cancel the shine. The resulting lag is perfect for an attack. A technique I like to use that works moderately well is to fire a fully charged shadow ball at the Fox/Falco, then wait for them to reflect it. Once it clears the area right in front of them, do a short hop teleport right in front of them. If done properly, you will then be able to attack them before they can respond. The best form of attack at this point is usually a grab as you don't have much time before they recover from the lag.
I do like your upthrow to fair combos, I have not seen that before. Normally my fair combos involve dtilt or dthrow.
A lot of your movements seem jerky and a bit out of place. It seems as if you are a bit hesitant and rushed in some of your movements. The only fix for this is to just keep playing Mewtwo and continue improving on your feel for the way he moves.
Do you by chance not use the c stick? If not, I recommend immediately learning to use that. The up air move is a very good move. There were a ton of opportunities to use it in your match that went unused. I recommend to take some time and truly learn the feel of every one of your aerials. Once you have them mastered, you will be surprised with how many options open up.