Move the green player up one space then left once.
Move the blue player up twice, down once and right once to drop the bomb.
For this bit, you need to be fast. Collect the silver key, then push the rock through the log, then take both players to the room below, avoiding the rocks and bomb blasts. If either player dies, restart. Go to the room full of bombs.
Get the blue player to collect the crystal top - left of the upper left corner of the bombs. Get the green player to collect the crystal next to the gold safe and move down one space.
This bit may take a few attempts. With the green player, drop the rock, and just before the rock hits the bombs, get the blue player to push it right. If done correctly, the rock should now be safe on top of the mass of bombs.
Get the green player right of the cyan key, and the blue player right of them. Move both players left at the same time.
Collect the two crystals next to the laser bean with the blue player. Take them to the top room. Take the bottom crystal in the crystal wall supporting the rocks, and head directly upwards. Collect the remaining crystals in this room.
With the blue player, collect the gold key. With the green player, collect the crystal where the gold safe was.
Take the blue player through the teleporter in the red safe room. Collect the red key. With the green player, collect the crystals in the room with the teleporter. Take the green player through the teleporter.
Move the green player to the space below the rock next to the laser. Bring the blue player to the right of it. Get both players to move left at the same time.
Take the blue player down one space. Move both players left at the same time twice. With the green player, take the two crystals on this side of the room, go under the rock and shuffle left then right.
Take the blue player through the teleporter, and the next one. Collect the Orb - Crystal and you've completed the Two - Player levels!