ok the roars were fine, because they're something more of a concept. But lets say you give a webbing like root to a bird of prey, or horn toss to a porcupine, they wouldn't make logical sense. and I kind of like to be able to associate the pet to it's ability. w/o their skin matching the ability we would be very confused, and it would be kind of like that monk that you keep staring at cause your not sure if he's a rogue. I think this idea would work but I don't think it'll be clean.
If I recall right (going off memory, my notes are on my other PC).
Fear (Tremble in place, not run around)
Intervene ability - i.e soaks a single hit
Nothing like spider webbing, or other anatomical limitations.
Also - freaky close on the roars. Swap Master for Stam (Mastery + Crit, Stam + Stats).
The Utility moves do have a strong bent towards PVP, but each of them will have some use in PVE mechanics. The pet choice is meant to be personal, the move/utility you want is going to be available regardless of pet family.
Also note: Some of the moves your pet learns cannot be auto-cast, and will instead use the hunter's GCD. Basically, it is like your pet is a glyph that teaches you the ability. FOr instance, the B-Rez mechanic won't be limited on your pet's GCD, but you will have to have that pet active (either as primary or during Stampede) in order to use it. Only 5 abilities to choose from, in an effort to limit potential keybinds. All pet abilities that can be set to auto-cast use the pet's GCD.
End Result is, your pet has the following customization:
Specialization (Target Swap, Tunnel Vision, "Tanking") - 2 debuffs based on choice
Buff - 2 effects or Bloodlust
Utility - 1 effect, including BRez
Exotic Ability (BM Only) - Choice of 5 "enhancements"