In the July 9th issue of Total Guitar Magazine there is an article about Billie Joe's guitar playing. The article talks about his playing, equipment, and techniques. Also included in the magazine are a couple pages of tabs that show examples of Billie Joe's powerchord riffs, octave melodies, unison blends, and double stops.
'Billie Joe considers himself a song-based player in the mould of the Who's Pete Townshend. An essential ingrediant of his rhythm style is his picking attack: he uses a heavy pick and a strumming motion that fequently swaps between constant downstrokes and alternating downstrokes and upstrokes.'
Source :
Green Day Authority