So Fusion is basically like a Kyuukokukai for Bountous.
1) Only a Legendary Bountou can train for Fusion
2) You must have at least 500 posts to begin training
3) Your training must be at least 5 pages long. You can train on your own or with a partner
4) Do NOT post one liners or the number of pages you'll have to do will be increased
5) Doll Fusion is NOT the same as Bankai. It can have only ONE ability. That means you cannot add up abilities to your Doll Fusion Mode as your post counts goes up
6) When you're finished training and it has been approved by the admin you can Post your Doll Fusion ability in your Bountou Doll thread