GBA- Power Rangers: Wild Force

In this isometric beat em' up game you select one of six Rangers (Lunar Wolf Ranger isn't playable until you complete the harbor level) as your primary player, then select three back up rangers, who you can summon for additional attack power throughout the level. You fight minor enemies called putrids until you encounter the final boss for that level. Once you defeat the boss for that level, he will grow to giant size, and you select a MegaZord combination and fight the large monster, hitting the A button whenever it appears on the screen (successfully hit all of the flashing A buttons and your MegaZord will launch a special attack). This pattern continues until you finally beat Master Org, and win the game.