Ah, thanks for reminding me.
So then, a Perish duo could be:
Smeargle;Own Tempo @ Wide Lens/Focus Sash
-Perish Song
-Dark Void
-Follow Me
-Protect/Light Screen/Reflect/Captivate/Lunar Dance/Filler
Wobbuffet @ Leftovers
-Counter
-Mirror Coat
-Safeguard
-Charm
Smeargle does all the work, putting people to sleep if needed, and starting the Perish Song. While it's in effect, Wobb does everything he can to stay alive, blocking status with Safeguard and crippling Physical Attackers with Charm. Smeargle can help keep Wobb alive by using Follow Me, and help keep himself alive with Protect, or follow Wobbuffet's example and dampen attacks with Light Screens, Reflects, or Captivate. Honestly, he's done what he needed to do if he pulls off Perish Song; after that, he can do whatever, so long as Wobb is still alive.
One nasty thing he can do if Wobb is on his last legs is this:
1) Switch out Wobbuffet.
2) Smeargle uses Lunar Dance and dies.
3) Pick Wobbuffet, and he's back, good as new, and not under the effect of Perish Song!
I'd still keep Dugtrio in the wings, just as a contingency plan in case Wobb does fall; he's not as effective, but hitting nonfliers and nonlevitators is better than hitting none at all. Plus, I think it'd be hilarious if the person puts so much effort into felling Wobb, only to find out he's still stuck in.