How do you improve box space on pokemon black and white?

Question

When I had just used poke transfer for the second time my box space increased from 8 to 16. How did this happen and is there a way to increase it more?

Comments

Well, in a long-run it:
1.)  Had nothing to do with poke-transfering
2.) When you put a pokemon in the last slot in the last box and exit and come back to the PC, it thinks your box is full and gives you more room.
3.) No, you can't increase it more.

Answer 1

There are 24 boxes in all. You start with 8. If you have at least one Pokemon per box, you go to 16. Then you go to 24. You just have a load of Pokemon, that's all.