What I mean is if i'm catching a legendary and you no it takes a while say 20 turns would it be better to use a timer ball an ultra ball, or are there any other balls that would be better?
(Catching power included)
It depends on the generation, but Timer Balls will almost always be better than another Poke Ball eventually.
From Generation III to IV, Timer Balls have a better catch rate than Ultra Balls after 11 turns, and better than Dusk Balls after 26 turns. From Generation V to VI, Timer Balls have a better catch rate than Ultra Balls after 4 turns, and better than Dusk Balls after 9 turns. From Generation VII onward, Timer Balls have a better catch rate than Ultra Balls after 4 turns, and better than Dusk Balls after 7 turns.
Timer Ball (Bulbapedia)
