If I was you I should breed the prankster Sableye with the ditto first until you get a female prankster Saybleye.
Since if I recall it right: A male pokemon has a 60 percent chance with passing on the ability when breeding with Ditto but the female has a 80 percent change that it will pass on its ability when breeding with a male or a ditto. So if you put the female and male together first you have a bigger change that you will get a offspring with the females ability than the one of the male. This can take a lot of time so as I said before: I recommend putting your male sableye in the daycare together with the ditto.
Since if I recall it right: A male pokemon has a 60 percent chance with passing on the ability when breeding with Ditto but the female has a 80 percent change that it will pass on its ability when breeding with a male or a ditto. So if you put the female and male together first you have a bigger change that you will get a offspring with the females ability than the one of the male. This can take a lot of time so as I said before: I recommend putting your male sableye in the daycare together with the ditto.