Hi. I just want to confirm that the list of supported cities are also valid for yikatong card?

If you buy a card with China T Union logo, you can use it many other cities that joined China T Union network. It is not 100 percent possible, some cities are not ready yet to accept your card, maybe 90 percent now. If you buy it in Beijing, it can be only topped up within Beijing. Also, you can get refund only in Beijing. Each city in China have different policy about transportation card. It is better to buy a transportation card in big cities with subway network.