"Zach"
While this technically spells the name phonetically, it's not a common or natural-sounding Polish name.
If you're looking for a more Polish-sounding name that is similar to Zach, you might consider:
* Zacheusz (although this is a biblical name)
* Zachariasz (also biblical)
* Zbigniew (meaning "conquering glory")
Ultimately, the best way to choose a Polish name for "Zach" would depend on the specific context and desired meaning.