How to beat it.
I am going to talk you through this step-by-step.
Ok walk into the room and see the Flaahgra Enter Scene.
Shoot the Mirror that is reflecting light onto it.
It should roar and fall inside the flower.
Roll into a morph ball and roll through the tunnel where the Flaahgra's vines had been. Bomb the Bomb Slot. You will return to normal. The Flaahgra will come back up and two mirrors will shine. Shoot one of the Mirrors. Kepps shooting it with the power beam and it should get stunned. Run over to the other Mirror and Shoot a missile at it. It will fall again. Roll into a morph ball again and bomb the bomb slot.
You will be normal.
3 Mirrors will shine.
Shoot 1 mirror. Stun it by keep shooting it with the power beam. Run to the second mirror. Shoot it with a missile. Stun the Flaahgra again. Shoot a missile at the other mirror. Bomb the Bomb slot again. Now 4 mirrors will shine (the last bit) Shoot a charged power beam at the 1st mirror. Stun the Flaahgra. Shoot the other mirror with another charged beam. Stun it again. And repeat until all the mirrors are flipped up. The Flaahgra should die and you will get the Varia Suit!
Note: if you ignore the bit where i say stun it, the flaahgra will flip the mirror back down so make sure you stun it or you will have a hard time beating it. Hvae Fun! Hope i helped!