Does Pickup work if the Pokemon isn't first in the party? (Pickup's page doesn't say.)
After winning a battle, any Pokémon on the team that has this Ability and is not already holding an item has a 10% chance of creating a held item for itself, even if the Pokémon was not used in battle. This Ability is still active while the Pokémon is fainted.
In the above lines.it did not say anything about being first in party.So it safe to assume that it does not need to be first in party.
Source 1.
Source 2:Experience.
Nope. Pickup works if any Pokemon in your party has it. Source: Experience