This thread is in relation to the first x-death battle (in world two)
But seeing as you mentioned it If your going to Mime Bahamut in the final battle, use X-magic to summon him twice then mime that so you mime both Bahamut summons. Or you could go all out and use X-magic-bahumut-Quick-Bahamut-Bahamut-Mime effectively having one character use him five times in a row