Intro - Crab 2

X should leave after the first crab encounter, leaving you in control of Axl.

Unlike X7, hovering with Axl requires pressing jump again. Use Axl's hover to cross the first large gap.

Beware the enemy near the end of the section before the door if the little bulb enemy attaches - getting bodied by it is almost a one shot kill.

Encounter room

For the encounter room, get Axl onto the right ledge near the door, look left, and just hold attack. Adjust aim as needed, and kill them as fast as possible.

Grab the gems while the door is loading.

Crab 2

Zero joins before Crab 2.

The second crab is actually a tutorial for using the Team attack. The small crabs always drop team attack crystals - grab them until the meter is full. Get close to the crab's head, and use the Team Attack button when it comes out from behind the waterfall.