As Wayne said the gar will do damage to all. Oscars grow at quite a quick rate, quite passive when happy, and IMO wouldn't put but one to 100g per fish. The parrot's (hope they're not dyed) depending on what kind as King Kong Parrots can be very aggressive. The true KKBP or BP does not like their surroundings moved once they have moved the plants, gravel, etc., to their liking when you move there habitat, they will attack you. Jewels can get aggessive but usually in pairs.
Plecs, that's Pure's specialty.*thumbsups
At least they are all small and you still have time to to watch their growth and temperaments and act accordingly.