The Barathu initial stat block is as follows:
SIZE: MEDIUM
8 HP
SPEED: 25 FEET; FLY 20 FEET
LANGUAGES
Common, Brethedan
Additional languages equal to your Intelligence modifier (if it’s positive).
Choose from the list of common languages and any other languages to which
you have access (such as the languages prevalent on your homeworld).
The Adaptable Limbs feat is as follows:
You grow sturdy lower limbs that allow you to walk on land. Increase your Speed to 20 feet. Additionally, you gain the Adaptive Locomotion action.
Adaptive Locomotion [one-action] (barathu, morph) Frequency once per hour; Effect You transform your limbs into either flippers or hooked pseudopods, to better traverse the surrounding environment. If you select flippers, you gain a swim Speed of 20 feet. If you select hooked pseudopods, you gain a climb Speed of 20 feet. This transformation lasts for 10 minutes.
Notice it says "Increase your Speed to 20 feet." Which is a decrease in the Barathu's base land speed. So I'm wondering, do Barathu normally never walk if they don't take this feat? If so, then the 25 foot speed should be removed from the base stat block, and the adaptable limbs should read that it gives you a 20 foot LAND speed. Or, if they do walk normally as well as fly, then the feat should just be about giving them a +5 ft speed boost with the Adaptive Locomotion swim and climb speeds. As for climb speed, it seems pointless, since they can fly naturally, but there can always be conditions that crop up that may make flying hard (like high wind speeds).
