You should have at least one adrenaline orb. Use it at the start of the battle. It will make the Pokemon call for help more often. As well, use the power belt, which gives you 4 extra evs of defense, as well as the other evs. One more thing, try to get an electric move to KO one of the pelipper when there are 2. [EDIT] The three abilities intimidate, unnerve, and pressure increase the chance of calling. Hope I helped!
