Hello,
I am new to the XBee Pro and I didn’t buy a developer kit. My question, can I power my XBee Pro with the 3.3v and then connect Tx/Rx/gnd of my laptop serial port and send characters wireless to another XBee Pro with 3.3v/tx/rx/gnd connected to another laptop, basically a wireless serial cable?
Or do I require a developer board or adaptor???
That is pretty much how they work — BUT you need to use some kind of interface to translate the (supposed) ±12V signals from the rs232 port to +3,3V for the Xbee. otherwise there is a danger of letting that expensive smoke out 
Charlie
so do I need a RS-232 to TTL converter on the TX side and a TTL to RS-232 on the RX end?
Yes that’s what you will need. The converter chips are super common and not very expensive. With a little Internet searching you can find various hobby websites that probably already have the breakout done for you for cheap.
Digi sells their development boards XBIB-DEV-R, or they also have the schematics on their website as well.
FTDI make a great interface cable - usb-5v ttl, and I think there is a 3v3 version also.