[bettababy]

Good job Blue... what he said...<giggles>
And, I'll add that the red tail and rainbow sharks tend to reach 6 - 8 inches, and are very aggressive and territorial. I would never do this in anything less than a 55 gallon tank with a few other larger, fiesty fish. These sharks also tend to spend a lot of time hiding, they are bottom dwelling and nocturnal feeders.
Agreed with Blue, no bettas in a community tank, that's asking for problems... and never a male/female pair together longer than the actual spawning. Dwarf gouramis are a good choice, but please be forewarned, it's difficult to find a female, and the females have almost no color to them at all. This is the reason they are not typically stocked, as they don't tend to sell well. Not a very "pretty" fish to most people.
If you want a lot of color, try a few male cherry barbs, they could cycle the tank for you, then work with male odessa barbs. You'll get bright reds and yellows this way, and the fish will all get along and not get overly large, but large enough to enjoy them.
Another option, and not compatible with barbs would be the dwarf cichlids that Blue mentioned. In a 30 gallon tank I wouldn't add more than 6 fish total, especially if you pair them, and expect A LOT of fry, as they tend to be good parents. With this in mind, you'll want to have another large tank standing by to house the many fry you'll find yourself with quick enough. A lot of pet stores will only trade, not buy fish, and this will depend on how much space they have and what their current market is for that kind of fish. I wouldn't add kuhli loaches if doing dwarf cichlids, and be forewarned that most dwarf cichlids require softer water and warmer temps. If you want "easy", I'd stick to the smaller species of barbs, those known to be less aggressive. With the barbs, if floating plants are provided for shelter and not too many less aggressive barbs (4 cherry barbs and 4 odessa barbs) then you could add a male dwarf gourami.
Be careful not to add all of the fish at once, and make sure the tank is heavily decorated for territory and hiding places.
And, also as Blue mentioned, 1 flying fox, I wouldn't mix the 2 species, nor would I keep 2 of either in that size of a tank long term.
Trying to spawn tetras in a community tank is almost impossible, I wouldn't even suggest trying it. Something like that takes a large tank with a lot of the same kind of fish, and seperation once the eggs are laid. Not all fish are good parents.
The barbs and dwarf gourami give you red, yellow, and blue and not overly aggressive... will that work?
Mystery snails are fun, and would work with the barbs/gourami mix, also. They're great for eating algae and waste in the tank and can get quite large. One of those with some cory catfish, or even a botia loach would work well.

 

[bettababy]

Same thing goes for the sharks... that simply isn't a big enough tank for any of the shark species, and the smaller ones, such as red tail and rainbow, as they mature, get very aggressive and tend to eat other fish in the tank.
As Blue pointed out, as they age, the flying foxes will usually get aggressive with each other, too. You may find later that you have to seperate them in order to keep them both.
The barbs I suggested would be compatible with the fish you already have, but not with the livebearers.
And, easier to breed or not, the chances of any egg laying fishes spawning and any eggs surviving is slim in a community tank. The pleco would have a feast, but you are welcome to give it a try if you like.
Sometimes in the fish world we have to weigh pros and cons, and while we can create a list of criteria we want in a single tank, that is not always possible, be it color or specific fish, breeding, etc.
Keep in mind that a 30 gallon tank really isn't very large, so even with medium sized fish, there is limited space for animals. The bushynose plecos average 5 - 7 inches full grown, and eat a lot. If the tank is heavily planted, especially as the pleco gets larger, expect any wide leaf plants to be eaten. If enough plants are provided, the pleco will feast on these and not bother with the algae on the glass and rocks, where it would otherwise feed. With that in mind, eventually, that pleco is still going to outgrow a 30 gallon tank, regardless of tank mates. The flying foxes tend to average 4 - 5 inches, so with those and the pleco, your 30 gallon tank is already half full.
I'm sure this isn't quite what you wanted to hear, but this forum is all about providing accurate information and healthy suggestions. For us to suggest a shark of any species, or some of the situations you have described wanting, then we would be partially at fault when you attempted it and ended up with a mess. 30 gallons won't sustain all of that, and a community tank is not a common breeding place, even to expect "a fry or 2" to survive here and there... it's just not a likely situation unless you're working with livebearers.
We'd very much like to help, but in order to do so, you'll have to make some definate choices about what is most important to you.... because unfortunately, in this situation, you can't have it all.