Jolly, as it ups Speed and lowers SAtk, which you don't need on a Physical Kadabra. You need the extra Speed. Remember that Physical Kadabra isn't good, and is outclassed by other Physical Psychic types. Special Kadabra is much better. If you do opt to go for one, go with a Timid Nature (+Speed, -Attack).
Probably the best it getswith Atk, SAtk is much better.