Concrete Man: Created to construct a dam, Concrete Man has integral knowledge of the process and the tools to make it happen. He has stubborn personality and has been known to tell off any lazy robots. Stupid, lazy robots.
Weapon: Concrete Shot Creates a temporary foothold as soon as it touches the ground. It can also be used to stop enemies in their tracks.
Tornado Man: Works for the Weather Manipulation Office to help control and stop the formation of large storms all over the world.
Weapon: Tornado Blow Launches a huge tornado that covers the entire game area. Heavy enemies will take damage, but lighter ones will be blown entirely off-screen.
Magma Man: Magma Man serves as the safety control robot at a large geothermal power plant. He is able to work in incredibly hot environments and loves to visit hot spas.
Weapon: Magma Bazooka Shoots a cluster of fireballs that spread out after launching. It can also be charged by holding down the shot button.
Come on, now. Do I really have to go on about THIS? Enjoy the new boss art, high res copies coming soon. Also, make sure to check out the source for a LOT of screenshots.
Source: IGN: The Bosses of Mega Man 9