Can someone counter a creature ability with a counter target creature?
No, you can't counter an ability with an effect that says counter target spell. You can only counter a spell

One of the reasons why people play  aether vial, because you can't counter creatures put into play with aether vial



You need to pay attention to the wording of the ability.  Because if the ability says that you can "cast" the creature such as  Garruk&#39;s Horde, than it does take the form of spell, and can therefore be countered.

But if the ability says to put it onto the battlefield than it's not a spell, and can't be countered