Storyline Events Leading Up to the Battle
When it falls to Shigeru Miiyamoto to rescue the fighters, half of them are on Shake King's ship. Miiyamoto must travel across the ship rescuing the fighters that are trapped on it. The Shake King appears just before you're able to rescue the last fighter(which just so happens to be the Male Pokemon Trainer).
The Shake King's fighting tactics are based off his boss battle in Wario Land Shake It!. He starts out with a shoulder tackle. If you jump off of his body while he's charging toward you, he'll trip, smack into the side of the screen become stunned. This gives you a perfect opportunity to attack.
He will also rise into the air and slam into the ground. While the initial phase of this attack is easy to avoid, it produces shockwaves along the ground. These are relatively easy to avoid.
His final attack is a ground punch that causes fireballs to fall from the sky. The fireballs are easy to dodge.
So overall, while his attacks are easy to dodge, they're extremely powerful if they connect.