Hint: Defeating Mecha-King Ghidora:
Use King Ghidora. As soon as the match starts and it roars three times (one for each head), jump and press B (multi kick). After Mecha-King Ghidora freezes, attack the light on its chest the same way. When Mecha-King Ghidora attacks you, do not dodge (just block) unless it jumps. Once it finishes, repeat the steps above until you destroy each head. Note: Try not to use special attacks -- they are not very useful.