i almost always get a critical shot with pokeballs about 50% of the time I don't use cheats on capture and not o powers is this just extreme luck or something I have done?
How many Pokemon do you have in your PokeDex? According to Bulbapedia, the more you have, the more common they are.
The probability of a critical capture occurring depends of the number of Pokémon that have been caught in the Pokédex. First, compute the value of "a" (the modified catch rate) as shown in the appropriate section above. Then, multiply a by the appropriate multiplier from the table below.
Main link: http://bulbapedia.bulbagarden.net/wiki/Catch_rate#Critical_capture