I've been playing pokemon for some time now. and I know how the pokeball system works for easy legendary like azelf or dialga:
( the "*" means "wiggle")
throw pokeball:
[0*,1*]
throw pokeball #2:
[0*,1*,2*]
throw pokeball#3
[2*,3* or catch!]
throw pokeball #4:
[3*,2*,catch!* or 1*!]
throw pokeball#5
[0*1*,2*,3*,catch!]
throw pokeball#5:
[0*,1*,2*]
(the rest are ones or zeros)
if you get to the fifth one try throwing a different pokeball intill it weakens, use another ball and so forth.



Explaining the guide
it's not that difficult, the [] mean the chances of the ball wigging. from left to right. here's an example:

see this:

that means the pokeball is most likely to wiggle 3 times because the symbol there 3* means 3 wiggles. so 2* is the 2nd likeliest one to appear because it is next to the 3* and so on.

Uh... actually, this is the equation:

Catch = PokeballEffect (((( 4 * Max HP - 2 * HP ) * Catch Rate ) / Max HP ) + Status + 1 ) / 256

For more information, see Serebii's Catching Page.

I figure that out from serebii a while ago. this is just to make thing easyer.