It takes some practice! The wattles tell them apart better right now. I notice the RIR cockerel has bright red wattles, and the pullet has next to none.
I agree, one of the Rhode Island Reds is a cockerel, which is a rooster under a year old. :hmm All the others look like pullets, and I'm seeing what are likely Sapphire Gems, the blue ones, Rhode Island Reds, and Red sex-links, which are the lighter brown ones.
How old are they? It looks like you have some Easter Eggers (the little ones lying down in the first photo), maybe a Sapphire Gem (the big blue one), a Buff Orpington (the little yellowish one), a Rhode Island Red or two (the dark red one) and a Black Australorp. I can't tell how many exactly...