How do you unlock biollante?

To unlock Biollante, you need to be a earth guardian in story mode. On the Level "Rumble in the surf", there is a building with green vines on it. I don't know if this is for ps2, but I found this on google.com. Destroy the building on biollante's head will rise out of the water. That's a good thing! then, you'll have to fight her at the end of story mode, or , you pick "rumble in the surf" again and you'll fight her. She is very easy (if you are Godzilla or baragon). Mothra is not really that good when fighting biollante. Since plants are weak againts fire, don't you think that godzilla's or baragon's fire will effect her! after you defeat biollante, she will be for sale in the store points shop thing.