I think it's completely impossible to fight him normally, like I have no idea how the game wants you to dodge all the shit he and his clones throw and you and the goddamn triple dash attack knocks you on your butt all the time and UGH. Completely incomprehensible mess, even without the sound. And yeah, you can just...not shoot the mech and wall-jump up it, what a great fight.
You also have figured out a key problem with the entire game in this level (and the last too): especially in the 3D sections, there is actually zero reason to ever fight anything, it's both faster and easier to just...go past the enemies. With hover and double jump, which you have from the start, it's even more comically easy. As I said: a non-game.
That would be neat, but we're talking about X7, so no, it does not coincide. It's either "rescue half the Reploids" (not a spoiler as many people have told raocow that), orVoltgloss wrote: Does the secret character becoming playable coincide with
the inevitable Sigma reveal? If so that might be part of the intention (to the extent there is one) -
a desire not to spoil the "surprise," that the bosses are corrupted by Sigma's influence, early.
reach the "Sigma" stages - but he is actually "revealed" after the seventh boss via very-obvious silhouettes and face closeups, and the CHARACTERS go "HWUH? SIGMA AGAIN???" only during the second Sigma stage.