I have 2 malabar puffers, 1 in a 55 gal and 1 in a 30 gal.
Puffy, a female (the one in the 55 gal) is housed with gold gourami, 2 dojo loaches, 10 cories, bristle nose pleco and spotted raphael catfish. They have lived together over 6 years.
I recently came across another malabar puffy, a little boy and I put him in the 55 gal. I thought they might get along since she is only 1 inch long, a female and in a 55 gal. She attacked the little boy immediately, biting his side and she would not let go until I pulled her off.
That is why the little boy is in the 30 gal with a betta and a few other cories.
From my own experience, Puffy gets along with everyone but her own species. And the little boy puffer is getting along with his mates. I have to assume the only way to keep multiple puffers together is to buy them at the same time.