Did sleestacks play in Star Trek?

There is no mention of "sleestacks" in the Star Trek universe. It's possible you're thinking of a different alien species or you've misremembered the name.

Do you have any other details about the species you're thinking of?

* What did they look like?

* What episode or series were they in?

* What were their powers or abilities?

With more information, I might be able to help you identify the alien species you're looking for.