Pickup - Rangi42/polishedcrystal GitHub Wiki

As in Gen. III onwards, a Pickup Ability Pokémon without an item held in the party has a 10% chance of gaining an item from the defined table at the end of a battle. Note that Pickup will also collect an item consumed by the opponent in front of the Pokémon with the Ability at the end of the same turn (i.e. during the battle) as in Gen. V onwards.

The game defines the Pickup item at pickup_items.asm and the chances at battle/abilities.asm as follows (the aggregate chance):

Item / Level	1–10	11–20	21–30	31–40	41–50	51–60	61–70	71–80	81–90	91–100
Potion	30%
Antidote	10%	30%
Super Potion	10%	10%	30%
Great Ball	10%	10%	10%	30%
Repel	10%	10%	10%	10%	30%
Escape Rope	10%	10%	10%	10%	10%	30%
Full Heal	10%	10%	10%	10%	10%	10%	30%
Hyper Potion	5%	10%	10%	10%	10%	10%	10%	30%
Ultra Ball	4%	4%	10%	10%	10%	10%	10%	10%	30%
Revive		4%	4%	10%	10%	10%	10%	10%	10%	30%
Rare Candy			4%	4%	10%	10%	10%	10%	10%	10%
Dusk Stone				4%	4%	10%	10%	10%	10%	10%
Shiny Stone					4%	4%	10%	10%	10%	10%
Max Ether						4%	4%	10%	10%	10%
Full Restore			1%	1%			4%	4%	10%	10%
Max Revive								4%	4%	10%
PP Up									4%	4%
Max Elixir										4%
Nugget	1%	1%
King's Rock		1%	1%
Ether				1%	1%
Lucky Egg					1%	1%
Destiny Knot						1%	1%
Elixir							1%	1%
Big Nugget								1%	1%
Leftovers									1%	1%
Bottle Cap										1%