Drake Hollow

This achievement is for uprooting one of each of the 27 types of Drakes in the game. They are randomised and will count whether they are found on the various seasonal islands, or your own little retirement island (when you level one of your drakes up to retirement age, they will go to the little island beside your base and turn into a statue, from which you can regain their buff. They will also leave two baby drake sprouts).
The drakes across the season can be revealed by climbing to the top of the lighthouse and holding x to gaze. Their locations will then appear as pale circles on your map. You can, as suggested simply save, uproot and reload on a single drake until this pops. If you are stuck between 90 and 96%, remember that the game always starts with Woodcutter and Lucky. Make sure to retire both of these to pull up a new drake of this type. If you are sure you have collected all variants, it may be worth starting a new game or re-starting a season from an earlier save just to drake-hunt.
The drakes will be randomised from the ones you do not have already, or have retired - unless you have all 27, in which case it will then select from all available drakes.

The 27 types are:
Aether Resistant
Ammo Scrounger
Attuned
Beekeeper
Blazing
Brawler
Craftsman
Curio Master
Electric
Explorer
Forceful Blows
Hasten
Heavy Hitter
Hunger Spirit
Iron Walls
Lucky
Mechanic
Nimble
Opportunist
Playful Spirit
Precise Striker
Regeneration
Tactician
Trader
Vampiric
Water Spirit
Woodcutter

Hope this helps, any additional information you think I may have missed, please comment.

Update: with the addition of sandbox mode it is now possible to get all drakes (including woodcutter and lucky) quickly and easily from this mode. Begin a sandbox game with whatever settings you like, there will be two random drakes in your camp to uproot. Manually save then uproot the two, reload and repeat until you have collected any missing variants. This method is also useful for the Saviour achievement, although I would recommend leaving both of these for last as you will pick up many drakes during your playthrough/s of the campaign for the other achievements.