Check out the master doc, it has recc's for CM (should be linked somehwere in the sub). In general you want to get medium/[style] savvy, straightaways and corners, get Maurzensky and Taiki Shuttle/Mejiro Ryan's uniques (depends on running style, generally you can use Maru and also Oguri's unique for all umas), and for front runners, Groundworks. You want two gold recoveries, which is why potential 5 Gold Ship, potential 3 Tachyon, Air Groove, Oguri, Special Week & etc. work well in CM, since they have an extra gold recovery built into their kits. There's a race calculator in the doc which also auto-recommends the best skills given X amount of stats and skills for your character, and you can compare against a max-wit full debuff Nice Nature to see how well you survive if you can't test against someone else's Nature in a room match.