This review isn't exactly top-notch, but I'll try my best to help you improve.
Once opon atime there was a Docter name Dr.Latios (Thats Me!).He only heals Latios's and Latias's becuse there use to be alot of them in the old days.But now there are two of them (1 Latios, and 1 Latias) , so everyone in theworld trysnot to catch one because they'll be put in jail. This is how the story starts.
with corrections said:
Once upon a time, there was a doctor named Doctor Latios. He only healed Latios and Latias because there used to be many of them in the old days. Now, there were only a Latios and a Latias. Everyone in the world tried not to catch one because they would be put in jail. This was how the story started.
"Once upon a time" is the WORST way to start a story. It completely destroys the seriousness of the story, and it's also cliched. Unless you're trying to attract kids under the age of seven years old, don't use it. The last sentence needs to go, too.
You also change verb tenses, which we all seem to be guilty of (some more than others). Choose one tense and stick with it.
Just a heads-up: self-inserts are VERY frowned upon (if not worthy of getting on Farla's bad side.)
Finally, I must question the condition of your spacebar, because there are times where you were supposed to separate words. You can see the corrections I made in the second quoted box.
Latios was flying over RustBoro City when he found a oran berry.Ovcuse, his heal was full, but he liked oran berries so much that he doesn't care whats going to happen.When he was eating it,a little more blood came into his body. Then, when he had finished it, he started bleeding. This one wasb't any kind of bleed, this one was a dangorus one called bletios. He fainted,then ,grendan (the pokemon emerald boy), came and saw what happened to latios. "What happend to him?" Grendan told himself. Then suddenly, Latias came and carried Latios to the one place he could get cured.
with corrections said:
Latios was flying over Rustboro City when he found an Oran Berry. His heal was full, but he liked Oran Berries so much that he did not care what was going to happen. While he was eating it, a little more blood came into his body. Then, when he had finished it, he started bleeding. This one was not any kind of bleed; this one was a dangerous one called bletios. He fainted, then Grendan came and saw what happened to Latios.
"What happened to him?" Grendan told himself.
Then suddenly, Latias came and carried Latios to the one place he could get cured.
More tense switching and spacing here.
On a more logical since, how could Oran Berries caused bleeding? Also, I didn't read anything about Latios cutting himself, so I'll assume that he was bleeding internally.
Also, DON'T describe your characters as "this character from (insert anime here)" or "that character from (inset game here)". Save that kind of stuff for author's notes, which should be placed at either the beginning or the end of the chapter/story.
Also, how could Latias carry a Latios? And why did Grendan say anything about Latias? In fact, why the Grendan stop in his tracks at the sight of Latios? If I saw an injured legendary Pokemon, I would at least ask myself where the heck it came from.
DR.LATIOS'S HOUSE
Grendan ran as fast as he could to Dr.Latios's hosue.When he opened the door, he found him trying to cure Latios. Grendan was relevid, he thought that Latios was going to die!But Dr.Latios suddenly said "I may not cure him....". There was a long silence, then Grendan said in a brave voice " you can't give up, your the world's greatest Latios and Latias Docter!" Dr.Latios cured him and Latios gave him the berry in which he got sick of. Dr.Latios told him in his own language to not eat more than one if his health is full. And this wasthe first time Dr.Latios had saved a Latios in 50 years.
with corrections said:
Grendan ran as fast as he could to Doctor Latios's house. When he opened the door, he found him trying to cure Latios. Grendan was relieved; he thought that Latios was going to die!
"I may not cure him..." Doctor Latios said suddenly.
"You can't give up," said Grendan bravefully after a long silence. "You're the world's greatest Latios and Latias doctor!"
Doctor Latios cured him, and Latios gave him the berry in which he got sick of. The doctor told him in his own language to not eat more than one if his health is full, and this was the first time Doctor Latios had saved a Latios in 50 years.
Tense got better at this part, but the spacing problem still remains. I'm getting the feeling that you haven't even bothered to check over this before you posted it.
Also, Doctor Latios cured the Latios rather quickly, and he talked to the Latios too. I'm sensing a Gary-Stu...
Overall, this story is bad. Why?
First off, the pacing was awful. A Latios got sick from eating an Oran Berry, a random kid finds Latios, and Latios is taken to the doctor and gets cured. If someone could summarize your story like that, there's some MAJOR problems with the pacing. Tell us how all this stuff happens.
Second, the lack of proofreading shows. Grammar, spelling, and spacing problems should not happen if you took the time and read over your work. Here's a tip: after you finish the story, don't look at it for at least 24 hours. When you get back to it, you're reading it from a different point of view. Beta readers would help you there as well. However, don't ask me to be one because I'm pretty bad at proofreading.
Third, your characters could use some work. Doctor Latios seems too good to be true (aka the definition of a Gary-Stu, the male counterpart of the Mary Sue), and the fact that he shares your username doesn't help either. Grendan is just a random kid, and Latios and Latias were just there (especially Latias, since all she did was carry Latios to Doctor Latios).
Fourth, description is nonexistant. Where are the characters? In outer space? On a farm? On the set of
That's So Raven? Don't expect the reader to be psychic (no TSR pun intended). You tell to let us KNOW what Rustboro City looks like, what the characters look like, and it wouldn't hurt to give the Pokemon some description.
Fifth, it's too short. Chapters should be a page long on Microsoft Word.
I give you a pat on the back for trying, but you have a LONG way to go in order to be a good writer. Read the advice threads and some of the fics that got
Frostweaver's Standard of Excellence. Maybe you will learn a thing or two.