I belive that is part of twelves story/ending. I also think they ripped it off of this website.
The gamefaq never tries to say twelve is top tier in gameplay and it cleary labels the description as STORY
go to the charchter select link and pick twelve . This is what it says:
The ultimate humanoid weapon. A killing machine that’s secretly self-aware. Twelve is the ultimate humanoid weapon. It’s a product of the G-Project which is part of Gill’s secret organization. Designed to be a stronger version of Necro, it has a fluid, shape shifting body. After completing the mission it returns to a capsule at a research institue to have its wounds healed and memories rewritten thus restroing it to its initial stage. However, this killing machine is beginning to become self aware, something which the scientists, including head researcher Dr. Kure, have not yet realized. With its protean body, Twelve’s unique combat style is based on constanly changing forms to become the optimal weapon for any giving situation. It also has the ability to copy every aspect of an opponent including appearance and abilities, giving it unimaginable power.