Variant of Schnorr Protocol (Difference pair of response and verification)
response $s=c(x+r)$, verify $g^s=(yt)^c$
  


This one doesn't work; a lying prover can chose $t = y^{-1}g^n$, for an arbitrary $n$.  Then, when the challenger responds with a $c$, the lying prover can respond with $s = nc$, satisfying the relationship.

The other two are good; the second is the standard Schnorr, and the first is standard Schnorr proof of the inverse relationship, that is, if you're proving the knowledge of $y^{x'} = g$ (which is equivalent to knowledge of $g^x = y$)