Easy Victories
Perform your character's super attack at the outset of the fight, then power up to 100%. Allow your opponent to power up to between 50% and 100% then press the D-pad twice to dodge your opponent's energy blast. Perform your character's super attack again, since your opponent will still be performing his energy blast and unable to move.
On the third level, buyto use as your character in battle. She is an android with infinite energy blasts that you can use to quickly and easily defeat your opponent.
When playing as Frieza, go above your opponent when you have 100% energy. Press A, press and hold B, then tap R to use the Certain Kill that Frieza used to blow up the core of Planet Namek. A timer will appear. Stall until the timer expires and the opponent will die instantly.
With Frieza at 100% energy, power up while pressing L, then perform a special attack. Frieza will turn purple while powering up and will increase in speed and strength, but his life gauge will recede. Use this technique once during the battle to avoid exhausting the life gauge.
Easy Special Attacks for Goku
With Goku Level 1 at 100% power, press L and R to unleash his special attack. Another technique for Goku Level 1 at 100% power is to go to the top of the screen and press A, press and hold B, then tap R to perform the Spirit Bomb or Genki Dama.
With Goku Levels 2 and 3 at 100% power, go to the top of the battle screen and press A, press and hold B, then tap R to perform a Kamehameha Wave with an Instant Transmission.