Upper Attack is a style of Beyblade attack in which the opposing Beyblade is lifted from the stadium floor. This is usually accomplished by using an AR that has a ramp-like slope that reaches under the opposing Beyblade and forces it to ride up the slope until it is no longer touching the stadium floor.
This style of attack is very effective because removing a Beyblade from the stadium effectively reduces its defense to nil. A strong upper attack can toss the opposing Beyblade from the stadium, but it can also be used to lower its defense and hit it while it is not touching the stadium in order knock it out.
Upper Attack Beyblades should focus on maintaining a high spin velocity and being low in height. If the opposing Beyblade has a higher spin velocity, it will be difficult to lift them. If the opposing Beyblade is shorter than yours, getting the attacking slope underneath them is more difficult. Finally, for Upper Attack to function correctly, both Beyblades must be spinning in the same direction.