Your Common Pleco could hit 24", so that right there is too large for a 30 gallon.
Your cons need to be in a different tank. (BTW, it's spelled cichlids...)
Your RTBS will need to be in a different tank, too. It is recommended that those be kept with other aggressive fish in at least a 30, but, with non-aggressive fish, you can't have a tank too large as they may have a hard time escaping the fury of the shark.
I think that the 3 gouramies could give you trouble in the future, too, as blues are known for their intraspecific aggression.
Your angel just might fit in in the 30, but will be snacking on baby livebearers until the parents meet their end.
All in all, I would think about another couple of tanks and returning the pleco.
HTH,
Matthew