I'm not sure what the dimensions on your tank are but RTS like to patrol their territory so a tank that's at least 36" long works best for them. Ususally I would suggest a 30 gal long at the least but the bigger the better.
As far as stocking compatibility I don't think that Angels and RTS are overly compatible since Angles tend to be more slow moving. The Guppies wouldn't stand a chance once the RTS starts to be grouchy and territorial. They're too small, too slow, and too easy going to hold thier own. RTS's don't really like to share their bottom space so I don't know what would happen between him and the pleco.
Sorry that's just my take on it.
