Also, you probably won’t see a Potters Leopard for a while as they’re a Hawaiian endemic, as for aggression it seems you are heading down a similar route I took in having peaceful with aggressive.
Id recommend a wrasse from the complex Rubriventralis as they show some excellent colours. My personal favourite is the Naokos as they’re aggressive but in most cases with the gang you have currently, he will remain close to the bottom.
I’d also add another Halichoeres or two personally. As for the leopards, I have also discovered Ornatissimus to be a rather more aggressive wrasse that will stand up for itself. So if you really want a wrasse I’d agree with the rest and go with the M. ornatissimus.
Why not throw a scottorum in too? (Kidding!) however, Melanomarginatus seems to be a more mellow species compared to what everyone says - Although yes they do lose much of their colour, I prefer the minor black patterning you see when right up close.
You will find your dragon will go up the chain in terms of aggression as she ages. The rest will most likely submit to the dragon being top of the chain, the coris could possibly put up a fight though depending on if it’s a true coris species (Aygula, Gaimard, Formosa ect…) and not a Halichoeres chloropterus or Halichoeres chrysus.
