From my measurements with various component leads and the female headers on the board you want solid core hook-up wire with a core diameter of 0.6mm to 0.75mm (0.3 mm^2 to 0.45mm^2)
If its not solid core then it won't be as reliable and I'm not sure what specification to use, perhaps about the same cross-section area of copper? Or use a bit thinner and tin the ends with solder to make solid?