He would still be useful in those two stances, as its versatility that makes him a great fighter.
I don't see how one character having 1/3 of a characters abilitys would make him useless. to me it makes very little sense.
Toro is definitely my main lol. I don't like using characters that are too main stream (Kratos/Raiden/Dante). I usually use a Red bandanna Toro, or the Bistro Toro/Chef Oni. Though the Casual clothes Oni form with the black suit and Afro really looks like Samuel L Jackson from Pulp Fiction!
Imo I find Oni stance the most powerful, his down triagle mochi explosion is so strong and nets alot of AP. I also like harrassing with Aerial Charged Mochi balls lol. Air Up Triangle is strong too. For the most part I avoid his square attacks, they don't seem to have much range.