SobblePlayz

Hi i was wondering if there is a way to increase the chance of finding a certain type of legendary pokemon for example zapdos or mewtwo because i have been searching for hours in the downstairs abandoned place in upper steelmorth but i cant seem to find a zapdos and the same in fungal cavern for mewtwo (ps i have defeated all of the kanto gym leaders,johto gym leaders,hoenne gym leaders and alola gym leaders)