Most people thought that the Eyedropper tool is used for picking colors or gradients in Illustrator. However, not much people knows that the eyedropper can be used for picking character styles and appearances. To do this, select the text you want to change and select the Eyedropper tool. Using the Eyedropper tool, pick the text style you want to copy from and it will set you current text to that new style.
You can also set the options you want to pick by double clicking the eyedropper to display the Eyedropper options window.
Appearance – Color of the text Character Style – Font of the text Paragraph Style – Paragraph settings of the text