oh sure, you could do that, if you don't like your guppies very much..........
seriously, all puffers are fin nippers, and the little dwarf puffers, can be the worst. puffers are best kept in a species tank if you like your other fish, so if you really want puffers, set up a separate tank for them. i have kept two in a 5 gal and 4 in a 10 gal, simple small set ups.