Normally I would need your whole team, but I think it's safe to say that Amoongus outclasses Vileplume anyday.
Although Vileplume has better Defences, Amoongus has a great HP stat, a useful Ability in Regenerator and a wider movepool, with useful support moves such as Spore, Rage Powder, Clear Smog etc.
One advantage Vileplume has over Amoongus is Aromatherapy, but given the fast pace of doubles, there's not much room for stalling, but it can be useful to get rid of annoying burns on your sweepers.
In the end, I stick to Amoongus, as it has a much better movepool than Vileplume, and is generally more useful in doubles.