Something I didn't take long to realize about Mega Man X7 that broke my heart:

Zero is worthless. Especially in the 3D level segments. As soon as you get X, scrap him.

In fact, I recommend you go to every stage and start rescuing those robots. You should have the 60+ needed for X after about 5 levels. Tornado Tonion is no match for X and Axl.

If you want a challenge, fight Flame Hyenard. He is HARD. Second hardest is probably Splash Warfly. Fighting Hyenard without Warfly's weapon is sure suicide.