peeps gonna have different views, which is great, but one of mine is
dont include live-bearers (traditional ones i mean), just too much of a pain in the rear with disease risk, wouldnt trust them in big tank, too much to risk, i am not saying they only fish that get diseases, i am just playing the percentages here based on experience
i have a 300 litre with live-bearers but its taken ages to get it this settled with mostly F1 and home grown stock
just my view........
I know the Guppy thing was a joke, just saying. My advice if you end up going community-type fish, strike off Guppies, Platies, Mollies and Swordtails.
I've got a few tanks that are busy, if it were my 5x2x2 i would go Oscars or something, a set up with just a few fish that get a big bigger than your average community fish. But i've already got a Malawi, if my Malawi tank smashed tonight (touch wood), i would set up another one, love it!!!!