Whenever I'm going to make a custom DC power cable, I usually use one of the online wire guage calculators. Enter parameters such as total wire length (there and back), estimated maximum current, that it is DC and not AC, and allowable voltage drop at the usage end. The calculator then returns a minimum recommended wire gauge to use. Selecting a heavier gauge wire will reduce your voltage drop at the usage end but at the expense of added weight and $. Once you know the wire guage then you will know what Powerpole pins to select.
Other things to consider when building a cable are the expected temperature range, permanent or portable installation, and rodent resistance.
If you will be using the cable in temperatures above freezing, then most insulations are likely fine. If you will use it in the winter well below freezing, then most insulations will NOT be fine, either getting too stiff or possibly cracking when flexed. For cold weather fexible cable I have been using high conductor count silicone insulated wire found in the hobby industry (HobbyKing, local hobby shop, etc). Very flexible, but the downside is the silicone insulation is also soft and easily damaged, so I then put the nearly finished cable in braided wire loom (many RV trailer shops, electrical suppliers). This also helps keep the wires together and from snagging. Some heat shrink at both ends keeps the braiding from unravelling.
If your target installation is permanent, you can get away with lower conductor count wire (I think standard is 7), but also keep an eye on the insulation as many modern insulations are vegetable based, and RODENTS love to chew on it. Mmmmm!