4 adult oscars are way too much for a 180g (adult bio-load plus territoriality); I had 2 in a 125g and it warranted nearly 100% water change a week in about 2-3 years time.
2 oscars with a giant gourami are way to much for a 180g (adult bio-load plus territoriality)
Jardini with a midas is way too much for a 180g (general aggressiveness)
The best one is a midas with larger dither fish maybe like boesemani rainbows, sailfin mollies, or giant danios. But if you can't stand the possibility of losing dither fish due to an aggressive midas, then skip the dithers.