Did not know that iridescent sharks can get nearly 5 ft long?
Not only that, but they're very active swimmers and they spook at almost nothing. It's not uncommon for iridescent sharks to spook, hit the glass and knock themselves out, and it's not unheard of for them to actually kill themselves by doing this.
The worst thing is that you can't hardly get rid of them once they get big because no one wants them. Big iridescent sharks aren't a rarity.
BTW, you put most small fish with an arowana or sunfish they're going to try and eat it so I'm not surprised that both of yours are already dead.
As far as your original question, all but the iridescent shark would work at adult size, but it's impossible to say whether they'd work if you started them at 3 inches. They have different growth rates and the oscar might snack on your other fish since they grow fast. Attitude wise they're all compatible.