Start with full lives - IEEOOALA

Start with 1 life - AEEOOALA

Infinite lives (except stage 4) - GXXLAAVI

Infinite lives on stage 4 - GZSOXPVI

Start with 10 continues - PEVELZZE

Bonus score now gives invincibility (instead of invincibility pod) - IYKNIKGX

Longer invincibility - YPSYPGIE

Even longer invincibility - ILSYPGIA

Double Dragon super punch - AOSEVAZA

Battletoads super punch - AOUEUAGA