My Platinum has boxes set up by level range (Eggs - 9, 10 - 19, 20 - 29, etc.).
eggs-9 = 22 Pokemon
10-19 = 27 Pokemon
20-29 = 22 Pokemon
30-39 = 21 Pokemon
40-49 = 18 Pokemon
50-59 = 16 Pokemon
60-69 = 4 Pokemon
70-79 = 7 Pokemon (Five of my main team)
Beyond that they are empty, except for my legendary box.
Legendary = 8 Pokemon