On Koboh, head towards the Fort Kah’lin meditation spot, then grapple up to the upper level, and follow it around until you find a load of droids on a landing platform, next to a Priorite Shard. Walking towards the shard will see the ground crumble beneath you, dropping into a boss fight with the Spawn of Oggdo. This throwback to the infamous Oggdo Boggdo boss fight from Fallen Order is tough, but defeating him allows you to open the crate in its pit to acquire the Poncho. Equip it in the customisation menu to unlock the achievement.