While training for E4, my six Pokémon (five battlers and HM slave) got Pokérus. My team at the time is as follows:
Hariyama (leadoff, as she has the least EXP)
Gyarados (this is where being Jolly really sucks, methinks)
Flygon (let me double check, because I think it has crap attack IVs or an attack-hindering nature of the wrong kind)
Wailmer (the HM slave)
(Yes, Flying types will wall this team, but that's why I am training.)
I suspect either Hariyama and Swellow got Pokérus (between two hours of trying to find Plusle, Volbeat, and Grimer to catch and four trainer rematches in which only those two were involved), but now all six have Pokérus.
Since none of my other Pokémon games has Pokérus (and I certainly didn't have it three hours ago), I need to bench someone so that I can transfer and spread. (I've beaten E4 in virtually every other Pokémon game, but none have Pokérus).
Now, this is probably a combined question: what's the best way to train for E4 and spread Pokérus? All the other games are in "breed and train" mode (I use XD for my item store, Emerald for breeding, FireRed to fill the dex, Sapphire is locked in Southern Island marathon catching battle, LeafGreen for Slowpoke, and Box to store my competitive battlers). Who should I bench to preserve the Pokérus? And who should my sixth battler for E4 be?
The clock is ticking now...