I think I can help out a bit, though I will be much meaner. |D
It's for your own good, though, and I apologize in advance about any possibilities of offending you, since I know I will be very, extremely, irrefutably, undeniably, indubitably, and most of all redundantly offending.
First, like Vato said, everything's way too short and lacking, and there are typos abound. I have to suggest you seriously look into getting a proofreader.
Now, appearance: "Big Black" doesn't just sound generic, but racist, too. I can't really put my finger on it (maybe it's the stereotyping), but it really does sound kinda racist to me. Is he six feet tall, bald or have an afro, have dark chocolate skin, the chest of the Old Spice guy, the legs of Michael Jordan and the priapism-suffering **** of a p***star? And how can he look like Shaymin? Is he albino, covered in grass and pink flowers, and have stubby limbs with no fingers or toes? How does his head look bigger than his body? That's just plain disproportionate! Lastly, how do you tuck your socks into your pants? Aren't the pants usually able to cover the socks in the first place? Just... this overall makes no sense whatsoever.
The personality's just a mess to see, too, and really doesn't fit at all. He's supposed to be a "Big Black" and he's /shy/? Being antisocial, by definition, also means he's unwilling or physically incapable of being friendly with people. It should literally be impossible for him to be able to say anything nice. At all. Now, what's "the best memory capacity"? Are you thinking of the guy who drew New York's entire skyline from memory to perfect accuracy? Or the lady who remembers every moment of every day of her waking life? (That's not "memory capacity", as you put it; it's a freakin' superpower.) The lack of social normalcy should eliminate any sense of understanding a regular person's feelings, too — a.k.a., empathy. Next, he's "shy and timid", and "can't really stand up for himself". Do you see the problem here about him getting aggressive when he's challenged yet? If not, I'll clarify it: it just doesn't work. Really, did you even try to check to make sure you weren't contradicting yourself? I don't think I can even understand it if you were rushed; it's just so glaringly obvious.
Lastly, and Vato's also cleared this one up, the history really says something about your sense of logic, and plot/canon in general. Why did the parents abandon their kids? (For that matter, where did the two younger siblings come from, since the "family of four" thing should count the parents that abandoned their four kids for no apparent reason whatsoever?) How did they survive? Especially the young'ns! Vato's stressed it enough, but I'm going to make it worse and just say, Team Rocket is not a terrorist organization; just a bunch of semi-organized thieves. They would never do something as hostile as burn down a school, let alone... anything. They also do not appear in the RP's canon. I can't even go into the rest of the history, because I don't understand anything in it!
As a final note, this reply was larger than your sign-up... by over two hundred words.
