Water Pulse have a 60 BP and its a Special Attack and may cause Confusion.
Scald have 80 BP and its a Special Attack and may cause Burn.
Mega Launcher - Increases the power of Aura and Pulse moves by 50%
Water Pulse's BP 60 + 50% = 90 BP x 1.5 (STAB) = 135 BP
Scald's BP 80 x 1.5 (STAB) = 120 BP
Confusion = 20%
Burn = 30%
GO FOR WATER PULSE BECAUSE ITS 135 BASE POWER AND SCALD IS 120 BASE POWER.