most zoans are pretty boring to use, with the more enjoyable ones being pteranodon, phoenix and axolotl, mainly because they can either fly, regen, or both. (plus axolotl has a funni model)
Barchiosaurus:
Brachiojaurus: Similar to other out of body abilities such as horo horo's or yomi yomi's, but it would let you slither instead of flying. The main body won't be able to move and it can be damaged. You can re enter the body just like horo horo or yomi yomi.
Brachiotoguros: While brachiojaurus is enabled, getting close to an enemy would allow you to grab an enemy with your entire body, which would keep them stuck and have you deal massive amounts of damage to them, similar to other grab moves.
Leopard:
Tail Grab: A move where you grab the enemy with your tail, making them unable to move and allowing you to land a good hit (like what Lucci did against Luffy with the Rokuogan).
Giraffe:
Kirin Hodai: Kyoku Bigan: A move where you pull your neck into your body, to then have it spring outwards in the form of a long ranged attack. Only usable in full giraffe form.
Pasta Machine: A short form (only lasts a little) which makes your neck shorter, but your arms and legs longer, giving you longer reach and more damage on slashing moves.
Mochikirin: You quickly slam the ground multiple times with your head. Only usable in hybrid form.
I know the models and animations are hard, but giraffes are awesome.
Other than that the main thing would be to remake some of the models, but i think these moves would make them more fun to use!