Proof.
Let us observe that given $V$ and $V \to Y$ as in (2) without any further assumption on $f$ we see that the morphism $X \times _ Y V \to V$ corresponds to a surjective morphism $B \to A$ in $\textit{WAdm}^{Noeth}$ by Formal Spaces, Lemma 87.29.5.
We have (2) $\Rightarrow $ (1) by Lemma 88.20.4.
Proof of (3) $\Rightarrow $ (2). Assume (3). By Lemma 88.20.2 it suffices to show that the ring maps $B \to A$ occurring in (3) are rig-étale in the sense of Definition 88.19.2. Let $I$ be as in (3). The naive cotangent complex $\mathop{N\! L}\nolimits _{A/B}^\wedge $ of $A$ over $(B, I)$ is the complex of $A$-modules given by putting $J/J^2$ in degree $-1$. Hence $A$ is rig-étale over $(B, I)$ by Definition 88.8.1.
Assume (1) and let $V$ and $B \to A$ be as in (3). By Definition 88.18.1 we see that $B \to A$ is rig-smooth. Choose any ideal of definition $I \subset B$. Then $A$ is rig-smooth over $(B, I)$. As above the complex $\mathop{N\! L}\nolimits _{A/B}^\wedge $ is given by putting $J/J^2$ in degree $-1$. Hence by Lemma 88.4.2 we see that $J/J^2$ is annihilated by a power $I^ n$ for some $n \geq 1$. Since $B$ is adic, we see that $I^ n$ is an ideal of definition of $B$ and the proof is complete.
$\square$
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