I've had a Blue spotted Toby for about 4 years now, and while a little smaller than a puffer, is similar enough that I think diet's would be similar.
I feed mine frozen clams, krill, prawn, squid, and silversides, in addition to my home-made mix. I find he likes the prawn and krill better than others, but feed everything to make sure he's getting a good variety. I didn't know that about their teeth, so am glad I do have 'shelled' foods going in.
- Mac