"Pun should be short for punch him in the mouth." /Ricky Gervais/
Anyway...
Liking the concept for the aliens.
Groups or even just a single one of them could change things up in combat, shifting strengths and weaknesses by alternating between forms. Especially when in a group, this could add more challenge to the player and make taking on even smaller groups more interesting.
With that in mind, there should definitely be more forms they could morph into, perhaps more swiftly the stronger they are. Turn hulk-like for tanking and damage dealing, area attacks. Sprout wings, for fast and agile attacks, either melee or range. Or both. Turning chameleon, by camouflaging themselves while being able to attach themselves to vertical surfaces and ceiling and either keep using their weapons (retaining their sentience) or start spitting something.
A Tsihu assuming one form can work in concert with another that assumes a different form. Buffing others in their group. Singling out players who either pose the most danger to them or scattering them to divide and conquer. The same way players could spot weaknesses and relay information to others, the Tsihu, being technologically highly advanced, could easily do the same. "Go for the lightly armored. Go for the frames with long-range, high-damage weapons! Slow down the fast ones! Keep them busy! Send the brutes to deal with their brutes! Need more fastness? You three, assume stalker-form! Surround them! Cut them off from the rest!"
Anyway...
Liking the concept for the aliens.
Groups or even just a single one of them could change things up in combat, shifting strengths and weaknesses by alternating between forms. Especially when in a group, this could add more challenge to the player and make taking on even smaller groups more interesting.
With that in mind, there should definitely be more forms they could morph into, perhaps more swiftly the stronger they are. Turn hulk-like for tanking and damage dealing, area attacks. Sprout wings, for fast and agile attacks, either melee or range. Or both. Turning chameleon, by camouflaging themselves while being able to attach themselves to vertical surfaces and ceiling and either keep using their weapons (retaining their sentience) or start spitting something.
A Tsihu assuming one form can work in concert with another that assumes a different form. Buffing others in their group. Singling out players who either pose the most danger to them or scattering them to divide and conquer. The same way players could spot weaknesses and relay information to others, the Tsihu, being technologically highly advanced, could easily do the same. "Go for the lightly armored. Go for the frames with long-range, high-damage weapons! Slow down the fast ones! Keep them busy! Send the brutes to deal with their brutes! Need more fastness? You three, assume stalker-form! Surround them! Cut them off from the rest!"