Is there any way to guarantee what Ability a wild Pokemon will have?

Question

I want a Suction Cups Inkay for chain fishing.

Answer 1

Well, it depends on how you do it.
No, there is no way to totally pre-decide what the Pokemon's ability will be, however there are ways to find out what your opponent's ability is.

An ability you can use is Trace, which you can find on Mega Alakazam, the Ralts line and the Porygon line. So just go around with a Trace Pokemon leading, and find your Suction Cups Inkay. Good luck!

Hope I helped. :)
Source: Experience

Answer 2

No, it's just luck; it's a 50/50 chance for Pokemon that have 2 normal abilities, and you'll need to keep trying if you don't get the ability that you want.

Source: Experience.