I discovered the problem. If you use a powersave to change the EVs of a Pokemon, that Pokemon will no longer be tradeable. But you can still change the IVs. I tested it on another ninetails and a regular Talonflame I caught and raised normally. Neither could be traded after I changed their EVs. I found out you CAN change the EVs. But you cannot make them 252 across the board because the limit is 510.