Ummm, dude,
if you havent cycled your tank, and you added all those fish at once, they are going to start dying real soon... Someone did warn you earlier in the topic. Check the info on cycling, and get yourself some test kits. Ammonia at least, but nitrite and nitrate if you can.
Also, does anyone know how big those sharks get?
Anyway: not trying to offend anyone, but I came into this thinking I knew everything as well, and ended up with a tank full of little corpses. Trying to stop it happening to anyone else.
Your guppies will be pretty big if they are pregnant. Probably best to post a question on the breeding forum. But if you dont want the extra fish at the moment (and if your tank isnt cycled you definatly wont) then just leave the guppies in there. Unless there is LOTS of hiding spots, the babies will all be eaten in about 5 minutes.