Hi, Here is what I have found on the web about your Valentini puffer. Though small in size, the Valentini can nip and and bite the fins of aquarium mates. It should be kept with other compatible semi-aggressive fish and will likely be aggressive toward its own species. The Valentini Puffer does feed on red algae, green algae, and coralline algae, but also likes to use its teeth feeding on crustaceans. It is definitely not recommended for the reef aquarium. Meaty foods it may accept include krill, clam, and carnivore preparations. Other sources say they can bite and they give off a poision if stressed that can kill your other fish. It also says that small crabs and snails will be eaten by the puffer fish. I'd skip the puffer.
I would put in the blenny and the clowns in at the same time. Then maybe the royal gramma and a pretty fairy wrasse (or a pair), at the same time. Then put in the tang and a smaller angelfish like a majestic (I'm partial to them as I have had mine for three years). If you are like me, only one large fish is best and you could have some fun with a couple of antheis if you only add one fish that gets large. I only have one lyretail antheis as I did not know how much I would like them....mine is the liveliest fish in the tank, not shy and very bright. Seems to like people. I just ordered him a female friend that will go into quarentine when she comes today. Lesley