4th Gen about abilities with field effects...

[Kiri Flicker]

If the pokemon in the first slot of your party has an ability that has a field effect (like synchronize) will it continue to work if that pokemon has fainted, but remains in the first slot?

 

[Sydian]

Yes, it will still be working even though it fainted.

 

[Gooberdued]

I use that technique when I search for items that can only be found on wild Pokemon. I send my trusty Nincada out, let it faint, and then keep it in my party. The effects of Compoundeyes still raise the chance of encountering a wild Pokemon with a held item, but now I can use my Sceptile with False Swipe so I can catch mass amounts of Pokemon easily and quickly.

 

[Shiny]

Yes, even if the "lead" pokemon in your party faints, their ability still works