You need a power amp, one that is bridgable to 8 ohms. Most guitar cabs are 8 or 16 ohms. Most small power amps are 4 ohms, 2 channels, for driving monitors.
If the power amp is "bridgable", you can combine the 2 sides for a mono 8 ohm output into an 8 ohm cab. There are some cabs, mostly for acoustic guitar amps, that use 4 ohm speakers, and you could drive one of those with one side of almost any power amp. As far as what kind of cab you use, it depends on what kind of power amp is driving it. You can also use a powered speaker cabinet, such as a JBL EON10 G2. I find the POD works best if you send it to a clean, flat, speaker system, and let the amp model create the character. In the studio, I use a Carver PM125 power amp and a 1X12 Marshall cab with
a Celestion Vintage 30. Live, I use a Fender PD250 passport PA, and it does exactly what I want it to do. Another trick in the studio for hyper-clean is to plug the POD into a powered subwoofer and one main, and set the levels on the sub lower so it doesn't overpower the main in the mix. Then put a good flat mic right in the near field of both speakers.
And yes- the POD works a hell of a lot better when you use it to drive a clean amp and cab, and mic it up. There is no digital substitute for moving air- yet.-Richie