So, if I have an LE Venom on his first click with Pounce and Vault, and I use Pounce, can I Vault after resolving the attack?

When Pounce resolves, Venom takes a click and loses Leap/Climb (and therefore does not have the necessary prerequisites to use Vault).

When the 'close combat action' given by Pounce resolves, Venom gets to Vault to a different position.

Which resolves first? Can I use Vault in this situation?

Actually, you can't use the two together because Pounce is a power action and Vault is a close combat action. Although they both may get you into close combat, they are different actions. Charge can be used with Vault but you would need that character to have Combat Reflexes.

DarkKnight20 is correct, but I want to address a misconception you seem to have:Pounce, as DK20 said is a Power Action, which grants the Pouncer a 'CC Attack' as a Free Action, not, as you suggested, a 'CC Action'.

Also, for clarity, Vault doesn't require an action of its own to activate, but will activate whenever the figure is assigned a CC Action, just like B/C/F, regardless of what other Power, Feat or TA that CC Action was used to activate.

Just wanted to clear that up.

BoT