When you get to the point were plants have shut down the reactor and beaten the spider ad you reach the plant guy shoot the spores that fly towards you stay out of the water keep blasting the plant guy with missiles eventually he will turn brown or purple and shoot plasma beams jump to avoid bottom beam crouch to avoid top one keep shooting charged beams and missiles and then when he turns into the spiky ball x do what you do to beat that one and absorb the large x to get plasma beam hope I helped
All you do is use a charged plasma beam to smash his gravity defier 1 jump he will float up 2 shoot the spinning thing Then get on the wall prime rockets and rapidly shoot his face you should be able to turn it orange then spacejump out of his way till he slows down and repeat I powned him in 2 minutes like that can you beat the time?
Ok just let yourself be hit by omega metroid Sa-X will come to the rescue ??? When HE gets whacked absorb him and he will give you the ICE beam the just go over there and FRY o.m.'s butt with it watch out though o.m. Can still stun you hope I helped