Did I lose my Nuzlocke?

Hi, so I was in middle of my Pokemon Black Nuzlocke and unfortunately my 1st pokemon in party, Watchog died to Cheren's Liepard on Route 5. I managed to defeat Cheren without losing any pokemon, but immediately after the match, Cheren healed up all my pokemon and we went to a fight against preschoolers, so my dead Watchog fought again.

What is the way to deal with this? Like is Cheren able to revive dead pokemonor something? Or did I just lost using a dead pokemon?