I feel like skills like howling or barking or snarling could boost your stats and debuff enemies too. Barking could probably cause an enemy to flinch or something which temporarily debuffs their Defense and Agility while Howling can increase Agility and Attack.
I'm working on a party of 2 game where one is a dog and this is how I'm approaching it. It'll also have the healing abilities and maybe one 1 or 2 attacks. The game is really about the other main character who in turn does all the damage.
Assassin skills?
I'd recommend looking at the Rogue's abilities and skill tree in WoW. They actually have an assassin specific skill tree.
How about:
oAn ability to go invisable/stealth and be untargetable by the enemy for X amount of turns. Or maybe he digs down into the earth? The more turns you make it, the less damage they do. Or maybe if they're only invisible one turn, that one turn does double damage.
oDebuffs are really your defining moves here I think. Blind. Confuse. Poision Debuffs that make enemies take more damage. Not just an armor reduxction, but a damage multiplier, maybe 1.5 or 2 times?
oPlaying on the stealth idea, id your using yanfly battle sequence or victor engine stuff, you can make it disappear off screen for x amount of moves and coke back that do that many times damage to one enemy, or hit that many enemies. (I dont know how youd do this, but I think you can.)
Since it's a wolf:
oDamage: Scratch, bite, pounce, knaw, chew
oBuffs/Debuffs: Howl, Bark, Snarle, Show Teeth
oThey are summon plugins and think it would be cool to have a wolf or dog howl and call/summon "the pack" and a bunch of other dogs/wolves appear and attack one to all enemies. Like a really high TP or MP ability, or it requires some kind of item or other resource so it isn't a game winner, but can act as a sort of "OH $#!+" ability, and I think it could be really well animated of you got good enough with it. And if you made it attack 3 random enemies and were fighting a boss it would attack it 3 times.
Good luck.
I want to know what you ultimately end up doing though.