You need to utilize the Shotlock from the Keyblades that you can find in the base game. DLCs, promotions, or any other Keyblade acquired via illicit ways is unnecessary. Usually, the Shotlocks missing are from Shooting Star and Hunny Spout because both weapons have three variations of Shotlocks. One is to use Shotlock non-maxed, the other is Shotlock maxed on a single target, and the third one is Shotlock maxed on three or more targets. The number of hits doesn't matter.