Ko^cky is not the variation of cats?
or also the basic form?
Kočka is singular; kočky is plural.
If it was the other way round, the only difference would be y==>i, right?
Ty kočky vidí psi.
If by 'the other way round' you mean "Those dogs see the cats." then yes, that would be "Ty kočky vidí psi." or more likely "Ti psi vidí kočky." depending on the emphasis.