Yoink!

Yoink! is 's  in Xenoblade Chronicles. It has a random effect that includes taking items, stat boosts, or points from the target.

Overview
While Yoink!'s effect is very random, it is always beneficial, and thus should be used as often as possible. Its item-stealing ability makes it a common way to take loot from enemies without having to kill them in an attempt to farm things.

Additional data
In addition to dealing damage, the possible effects of Yoink are:
 * Stat - Riki steals a stat from the enemy, applying a debuff and giving himself a matching buff. If the enemy resists the debuff that Riki tried to inflict, he gets nothing.
 * HP - Riki steals 50% of his max HP from the enemy, essentially dealing that much damage and healing himself for the same.
 * Strength - Riki gets +10%, while the enemy gets  +10%, with indefinite duration. If triggered multiple times, Riki can get up to a 50% boost while the enemy can get up to a 30% loss.
 * Ether - Riki gets +10%, while the enemy gets  +10%, with indefinite duration. If triggered multiple times, Riki can get up to a 50% boost while the enemy can get up to a 30% loss.
 * Agility - Riki gets +10%, while the enemy gets  +10%, with indefinite duration. If triggered multiple times, Riki can get up to a 50% boost while the enemy can get up to a 50% loss.
 * Item - Riki steals an item from the foe. Up to 4 items can be stolen per battle, which are obtained when the battle ends in victory or escape (but not defeat). Riki can steal duplicates of the same item in one fight, and stolen items are not prevented from also dropping in chests.
 * AP - Every member of the party gains 50% of the AP the enemy would normally grant. Requires the AP for All! skill.
 * EXP - Every member of the party gains 50% of the EXP the enemy would normally grant. Requires the EXP for All! skill.

Manual testing suggests that the selection logic is thus:
 * With equal chance, pick between "AP", "EXP", or "other". If the matching skills are not unlocked, remove those options before picking.
 * If "other" was selected, with equal chance, pick between "stat" or "item".
 * If "stat" was selected, with equal chance, pick "HP", "strength", "ether", or "agility".
 * If "item" was selected, generate a chest containing a single item using the enemy's typical chest and item drop rates, and give that item.

Riki cannot steal items, AP, or EXP from enemies that are 11 or more levels above him. If these options are selected and fail, Riki will steal a stat instead.

Some enemies are immune to items being stolen, but this mechanism is unknown.