I believe the following information on Bulbapedia is correct, but with 'base stats' replaced by 'stats':
The tournament bracket is organized as follows:
Left Bracket: 1 vs 9, 13 vs 5, 8 vs 16, 12 vs 4
Right Bracket: 3 vs 11, 15 vs 7, 6 vs 14, 10 vs 2
Seedings are determined by their ranking...