and E is good for bosses.

Empreror Palamecia
Cloud of Darkness
Zemus
Exdeath (originall release)
Kefka
Sephiroth
Edea Ultimecia
[strike]Kuja[/strike] Necron
Seymour

and L shows up a lot aswell! But that's the same as R in Japan

Laguna Loire
Squall Leoheart
Cloud
Cecil
Zell

and more...