In my experience, dwarf puffer nips at everything.
I tried cories, ottos, rubbermouth pleco in a 20 gallon tank.
I tried to introduce them to a community tank, 45 gallons+4 dwarfs puffers+other fishes (ottos, cories, bolivian rams, tetras)=one big mess
Everybody in the tank were nipped.
They can only live by themselves. species tank only... maybe with couple of ottos.