The included input capacitor should be installed on the ESC with the correct polarity. Recommended additional capacitors should be either Panasonic FM/FS series or Rubycon ZLJ series. The following image shows the recommended capacitor mounting on the F-Series 120F[X] ESC. Further capacitors should be mounted close to the input terminals in setups where it is needed (high power, long input leads, etc). For example, in a 10S F5B application, we recommend 3 extra 330uF 50V capacitors. The 200F3[X] has 3 capacitors mounted on the board, further capacitors are rarely required.
Please keep the capacitor legs as short as possible (keeps the noise to a minimum). Avoid using low power irons to solder the capacitors, as this can result in cold solder joints leading to issues and/or failures in the future with your ESC.