I think variety is very good advice--that's what we do for our cats, too.
As for the supplement itself, I'm not sure what AAFCO requires for approvals but can say that our vet sounded very happy about the ingredients I told her were in EZcomplete. She was particularly impressed with how great one of our cats, Ireland, looked at this year's exam. Ireland had always seemed very picky about her food but she's turned into a very eager eater since she's been eating one meal a day of cooked food made with EZc. I thought it might be the digestive enzymes but the vet suspects it's probably the pancreas. EZcomplete hasn't been available long and I've changed a few other things in the cats' menu (adding Feline Naturals and taking out Primal poultry foods) but I'm convinced that it's feeding EZcomplete for several months that has made Ireland a happier cat!
