Dang, you can't play with just 1 person... that stinks
You can play Triforce Heroes solo.
What's he's saying is that for the multiplayer mode, you do need a group of 3. It can't be just you and a buddy with an AI or an online random for the 3rd. Which is, in fact, annoying.
Decent game solo if you don't mind lots of tapping the touch screen to switch between your 3 characters, game is definitely better multiplayer and you CAN play with online randoms. I don't know how active the community is now though, I played back when it was new.