You can use this tool to go and see what monsters drop and steal which equipment in both a regular FFVA Rom and any patched such as the custom class mod. I don't have the time to go hunt down the answers myself but best I can offer.
Ok, checked the complete enemy list and no chance of get them, besides the extra steal i have found it was that twintania had 2 entries, didn't notice it before.
About cheat for them, i just want a good save, 100% bestiary, treasure collected and all possible items i could get, so no need to hack. I found weird that bunch of free spaces at the end of the item list and made a check to see what happens, and i found those faults, i were used to see all spaces used.
Thanks for the help, now i know that i didn't left anything behind.
It's worth noting that mutiple bosses are in fact the same sprite reused on multiple enemy values that switch from script (Chraging form) in the case of Twintania, These other forms tend to have different drops and steals as well. Kinda like how the Genji gear works.