puffers do best in a tank by themselves, but each of them have their own personality. The special ones have a personality that is peaceful; however, they may snap one day and kill all their friends in a few years. As juveniles, they are less aggressive. As they mature, the aggressiveness will get worse.
The best tankmates are the ones that hide a lot or stays out of the way of your puffer. I think its a gamble to have tankmates. If you don't get attached to the other fishes, then you'll be ok.