It depends a little on what you want to do. If you want a mixer to give you two (or more) good mic inputs with tone control and an option to run a backup music source from outside your controller, then a small PA mixer is your best bet. Currently my money is on the Yamaha MG-series (3rd gen) with the MG-06 being a great little unit. Also the new small Mackies are on my list.
If you want to have more DJs back to back, you could opt for a line level mixer (rack or desktop), but frankly they are hard to find and mostly made for fixed venue installations. Much easier and cheaper is to get a 4-channel DJ mixer. Which will most likely give you an extra (MC?) mic channel too.
In the case of the PA mixer, expect most of the inputs for mics to be XLR, combo or 6.3mm Jack. Line level inputs typically 6.3mm Jacks, TS or TRS depending on unbalanced or balanced input. The MG-06 has two stereo channels that let you hook up unbalanced Jack TR connectors. To hook up your controller you can go RCA to TR-Jack or XLR to TR(S) Jack. As long as the distances are short.
In the case of a DJ mixer, most likely every channel will have RCA line inputs. So simple RCA-RCA connection from controller to mixer.
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