Time out for the fish bully!

So, what do you do with a fish who's suppose to be a community fish but turns out to be one big bully!? We purchased 2 of the same as we were told that's the way to do it, by the fish experts of the local pet shop. We had 2 gold fish, one sucker and 2 blue gourami's. All seemed well until the 2 gourami's started to chase each other and didn't seem to like each other too much. Kinda hard to tell if a fish likes another fish I guess except you can definitely tell when they do NOT like each other. Scales go flying, fins get destroyed, etc. Anyway, the one gourami ended up dead in the water one day so we fished him out of the tank and made him go looking for Nemo. Now things calmed down in the tank until Mr. Mean (the other gourami) decided he better let those 2 darn goldfish know who's the boss of this tank. You must know my daughter brought those 2 goldfish home 1 1/2 yrs ago from school one day. They had done some kind of an experiment with goldfish and with parental approval they got to take a couple of them home. We ended up with 3 of them but 1 decided he needed to go look for Nemo so we were left with just 2. They measured about 1 inch and had a gray and white color, these 2 babies have grown into 2 big (and I'm talking 4 and 6 inches) orange beauties. Now the gourami measures about 3 inches I would say but he's decided to take on anything that moves in the tank. We've also gotten another smaller fish, can't remember what kind he is but I must say he's the smart one compared to the goldfish. This little guy hides in a log as soon as Mr. Mean decides to start moving his one-man-troop around! Now the goldfish on the other hand just hang out until they get bitten or pushed by Mr. Mean, then they take off and both of them try to fit into a log that's really made to fit only one fish. A couple of times I've thought I'd had to rescue them as they looked stuck but they managed to get out by one of them backing out and the other one just wiggled his way through the rock pile on the other end. Dumb fish!!!! Sooooo, we had to empty the tank the other day and stuck all of the fish in a 2 gallon tank for about 2 hours until the big tank was up and running again. We kept an eye on Mr. Mean when they were all hanging out in the small tank but they all behaved and did whatever fish do. But then, hoorayyyhhhh did we succeed without even realizing what we succeeded in ... when we put them all back into the big tank Mr. Mean was either in shock or thought he'd been put in time out (with his enemies) and behaved like a good fish should behave! That has lasted for about 3 weeks now and believe it or not ... he's now back at doing what he was doing before, chasing the other fish and stressing them out. I have now threatened him by putting him in with my Beta and see who will win that battle but since I'm an animal lover I just can't do it. But, something needs to get done ... the kid and my husband are ready to flush him down to see Nemo ... not sure if and when this will happen but we got to do something with that darn fish!!!