Tired of pulling sticks? Give kids 4 different buddies to rotate throughout a given time. Every quarter I give students 4 Clock Buddies. Then I simply have to shout out "Meet with you 3 o'clock buddy!" and my students are paired!
For longer use, mount and laminate clocks and use permanent marker to assign buddies.
I usually give one buddy that is the same ability, one that is opposite in ability, and then two other students that I think the student would pair well with.