1 Swimmers must be competent in all 4 strokes: Freestyle, Back, Butterfly and Breast
2 Swimmers must be able to swim both short (50 and 100M) and long courses (200 to at least 400M) competently - longer distances to assess physical fitness
3 Preferably swimmers have participated in Nationals Swimming Competitions for Primary Schools and SNAG Competitions - to ascertain their timings

swimming(dot)org(dot)sg/SSA/GET-INVOLVED/Your-Nearest-Club.aspx
Fyi.