While this is a great mod, I believe there are some missing fundamental features on mob abilities and in morphs, in general.
Here are some bits that I think should be added as optional, meaning the player can turn on or of these at will.

Universal ### Changes

• Morphs do not play the selected mob's idle sound effects or its footsteps. Since being silent and having default player step sounds ruins the immersion and makes you stand out from other mobs, this would make a great addition.
• Morphs do not have the corresponding movement speed of the selected morph. Not being faster as a Cat, Horse etc. makes these mobs cosmetic at best. On the other hand, slower movement speed for Zombies, Turtles etc. may also be considered adding.
• Mobs' HP cap should be optional.
• Hostile mobs do not retaliate (if morphed as a hostile mob) when punched.
• Hostile mobs should not attack if morphed to a passive mob eg. Pigs, Sheep
• Hostile mobs sometimes turn aggressive altogether if one of them is provoked (not just the mobs you attacked)

The Ability changes/fixes below are necessary and needs to be added.

Ability ### Changes

• Flying mobs are a bit inconsistent. Parrots flap their wings in a buggy way, Chickens don't flap their wings at all when floating etc.
• Mobs such as Endermen and Blazes do not emit portal and smoke particles, respectively.
• Guardians and Squids do not have swimming animations and do not move their limbs.
• Creepers are badly implemented. They should absolutely die after exploding once, destroy blocks, and do so in a fuse animation in which the player can cancel by pressing the ability button again before exploding, and iconically hissing when inflating.
• Ender Dragon suffers from fall damage and buggy movement.
• Wither does not play the correct sound effect for its ability.
• Wither should have its blue destructive skull variant added having a separate cooldown from the other one.
• Shulker has no abilities nor does it open its shell.
• Hoglins and Zoglins do not have attack animations.
• Polar Bears have no attack animations.
• Strays do not inflict slowness.

5th one i dissagree with i think they should still attack you bit if you get cloase to them 6th one dont change Ability Changes 2 if thats added please make it an config option defulted to on 5 not for me The Shulker one would be hard to implanimnt probley