Not too many users have played Gaiden (or, in my case, completed it). Can you please provide a source as to whereabouts the name of the Tyrant is given as "Amoeba"? I don't recall any Japanese guides being printed about this game, so can't order any from Jap-Sai to evaluate it.
I felt I should point this out because Riley intends to move the article to a different name if no citation for "Amoeba" is provided. Of course, you can always move it back so long as you tell us where the information came from.