How do you get the pegasus on Astro Knights Island ? – Entertainment & ArtsReport
At the bottom of the metal forest, you will find the Laser Lance. Pick it up, climb back to the platform, and go right to meet Sir Cador. Climb across the Phoenix Eggs to reach the cage, and use the laser to blast the lock open.
*To cross the eggs, jump when the next one is OPEN, so that you land on it when it is CLOSED.
(see related question)