Okay, you can find Adamantoise at the beach near dollet. They show up semi often there.

There is no other way that I know of to get a power generator, unfortuantely.

You can get a hero by mugging Seifer in every single battle that you fight him (except for one or twi times, when you can mug a holy war from him.) You can also refine cards into heros (I think) and you can refine the gilgamesh card into ten holy wars.

Also you can refine a bunch of hero trials into heros. Heros can then be refined into holy war trials, which can then be refined into holy wars. That's alot of effort though.