I would say yes that angels and oscars will go together. You will have to put the angels in first and get them to a good size ( I say them because they will do better in a school )then you can put in an oscar(One oscar , if you wanted to put in more that means bigger tank), but it should about an 1-,1 1/2 inches. Dont feed the oscar live foods that only makes them more agressive. And as Daveedka says you will need a big tank, 6 foot would minimun, i would say 8 feet to give them space to run if they (angels)get bullied.