Well, since you have lots of positive comments, let me be the one to give you a negative response. All your fishes here need different water conditions, and keeping them together is asking for problems.
OK, starting with the mollies. Both of these need hard, alkaline water, perferably with some salt added (i.e., brackish water, with a specific gravity of 1.003 being ideal). Mollies can be kept in non-brackish water, but spend some time in the livebearer section and you'll see a LARGE number of people with molly problems. I'd guess about 50% of the mollies kept in freshwater end up getting either fungus, finrot, or "the shimmies". Mollies kept in brackish water are many times less likely to have these problems.
Guppies need hard, alkaline water. They also do well in brackish water (even salt water) but they certainly don't need salt in the water. Kept in anything other than hard, alkaline water they tend to be sickly.
Panda cories come from soft, acidic streams and rivers with plenty of water current and open spaces to swim in. They live in schools of hundreds of specimens. Two cories = two unhappy cories, and they should really be in a tank that allows you to keep at least four or five, and ideally more than that.
Dwarf gouramis come from soft, acidic ditches and streams with virtually no water current at all (as is typical for labyrinth fish generally, with a few notable exceptions). They do not like water current that is strong, and lack the body shape or swimming strength to survive in such conditions. Kept in the wrong water chemistry they are VERY prone to sickness, presumably because their immune system is compromised, and the now-recognised DGIV (dwarf gourami iridovirus) eventually kills a large number, perhaps the majority, of commercially bred specimens.
In short, your mollies could work with your guppies, but not the cories or the dwarf gourami. The guppies and cories could live together, at a neutral to slightly alkaline pH and moderate hardness, and guppies usually do well with a bit of water current. The cories and the dwarf gourami make a poor combination because they prefer totally different water movement levels. Cories would work best with tetras, danios, etc. The mollies will (trust me) eventually need treatment for diseases because of the absence of salt, and adding salt would stress the dwarf gourami. So those two are a bad combination. The guppies and dwarf gourami need different water chemistry, and while both might survive in hard, alkaline water, eventually your dwarf gourami will get sick and die. With dwarf gouramis NOTHING helps more than giving them the warm, soft, and acidic water conditions these fish need. Forcing them to live in anything else is usually fruitless.
I'd highly recommend buying an aquarium book that provides you with water chemistry requirements and other information, rather that just buying species "that look nice". Use it when you go shopping, and trust the science rather than your luck.
Cheers, Neale
