Beyond basic action commands, advanced combat involves strategic use of badges and Star Power. 'Stylish Moves' (pressing A at specific moments during an attack) grant extra Star Power. 'Sweet Treat' (a Star Power move) can be used to heal and restore FP. Consider 'Danger' badges (e.g., Danger Mario) which significantly boost Mario's stats when his HP is low, allowing for high-risk, high-reward strategies. Learning enemy attack patterns for perfect guarding is also crucial for minimizing damage. Don't underestimate the power of status effects like Dizzy, Sleep, or Poison.
