Wow people, he knows how it can be possible, he wants to be able to find an easier solution. Read fully and don't copy other people's posts >_>
A good trick is to get alot of Max Repels, have your highest lv Pokemon in front, then go to I believe one of the guard buildings, use Max Repel in there (make sure it's in the building), then go out the building into the grass. This abuses the fact he runs everytime you enter a building, so walk around 20 steps, then go back in and out again. You might have to reset quite a few times, but it's surefire to work eventually.
My friend used it so I could get Raikou fast. The best guard building is the one near Vermillion to the right, since the grass is very close to the building.