first off, dwarf puffers are freshwater, figure 8s and green spot are brackish species.
secondly, while some have had success with certain combos, puffers should be kept in a species tank. puffers, all puffers, are fin nippers.
that said, you have a fw tank, so you could only get a fw species, but no puffers will work with your tank inhabitants mate.
consider setting up a tank just for puffers. go to the oddball section, read the pinned articles, go to some of the linked sites. do some research online to be sure you can handle the species you chose. understand the water it needs, the size it gets, the amount of room one fish will need (for example, just one green spotted is too big for a 10 gal tank...), find out about food and whether thats somehting you can provide (snails, frozen as very few will accept flakes, live, etc). if youre dead set on puffers, go with a 10 gal tank, lots of plants and caves, and good filtration. get four dwarf puffers max. dwarf puffers need approx 2 to 2.5 gallons per fish as a general rule, to give them enough "personal space" and to be able to set up their own territories and such.