Soon, Pokemon GO will incorporate a type of bonus that will improve the catching experience as a whole.
As detailed by Niantic, every Pokemon caught with this new feature will go toward a tally; catch enough monsters of a certain type, and future monsters of that same type will be easier to find:
We are adding a new feature which grants a catch bonus when you earn medals based on catching certain types of Pokemon (Kindler, Psychic, Gardener, etc.). These new bonuses will give you a better chance of capturing Pokemon with a related type. For example, as you reach a higher tier for the Kindler Medal, your bonus to catch Fire-type Pokemon such as Charmander, Vulpix and Ponyta increases.
Trainers can work their way to a new tier by catching many Pokemon of the same type. If a Pokemon has multiple types, your bonus will be the average of your bonuses for each type. For example, Pidgey is both Normal and Flying type. Your bonus in this case would be the average of your Normal-type and Flying-type bonuses.
In the post title, Niantic states that any player who utilises this feature will "increase the odds of catching rare Pokemon," which is pretty great. Pictures attached to the news update show, for example, that a trainer who captures 10 Poison types will gain +1 Poison Catch Type Bonus. No word yet on when this improvement will drop, but we'll keep you updated.