Mega Man Xtreme/Walkthrough

Normal

 * Storm Eagle: Not vulnerable to an available weapon.
 * Flame Stag: Vulnerable to Storm Tornado
 * Chill Penguin: Vulnerable to Speed Burner
 * Spark Mandrill: Vulnerable to Shotgun Ice

When you reach the core:
 * Zain: Vulnerable to Shotgun Ice
 * Bospider: Vulnerable to Shotgun Ice
 * Sigma: Vulnerable to Spark. In the second form, he only takes damage from the X-Buster.

Hard
Hard is available when you clear the game on normal difficulty.