When I go to the Flight Area there is a person block the way. I can't get..

A lot of people have had trouble figuring this out, but allow me to help you out ;)

To go to the Fight area on the left side, or to surf one the right side, you have to see all 150 Pokemon in Sinnoh, and talk to Professor Rowan, when you do all of that stuff, you will unlock the National Pokedex. After you unlock the National Pokedex, go back to the Fight Area path, and the people will be gone. If you have played the game, fighting every trainer you see, and training your Pokemon, right, then by the time you beat the Elite four champion, you should be able to go and get the National Pokedex.

All you have to do is beat Battle Tower

Hi halogod2 I can tell you where to find four pokomons 4 legendereis if you tell me how 2 put codes in so I can get 999 rare candy coz I don't know how to put them in and I really want them well any way go 2 proffesers rowans lab and theres a person in front of it talk to her and she will tell you 2 go 2 celcilst and when you get there go the house on the right hand corner go in the house and talk to the old women and she shows you a picture of it and it adds 2 you're pokodex and plz tell me how 2 put codes in plz......... And the other three are in sepreta places go 2 the three lakes and surf into the middle and theres a cave go int o the middle and there you go and thats the people gone and you're past them

Well it seems like you're stuck in the Fight Area. To get beyond that, you must obtain the National Pokedex from Oak in Rowan's lab in Sandgem Town after you've seen all 150 Pokemon in the Sinnoh Pokedex. You'll also obtain the Poke Radar from Rowan afterwards, but that has nothing to do with this.

With the National Pokedex, you go beyond the Fight Area in both the north and east. Enjoy your exploration of the Northeastern Island!