This comment includes SPOILERS on the matches, I tried to mark it as a spoiler but it didn't work ;( I hope this helps tho
Diamond no ace Act 1
Ch 1: Akagi vs Narushima Jr. High
Ch 8: Seidou vs Ichidai (Spring tournament)
Ch 10-16: Seidou intrasquad (1st years vs 2nd and 3rd years)
Ch 20: Seidou vs Yokohama Kouhoku Institute (Kantou tournament preliminaries)
Ch 23-24: Field A- Seidou vs Teitou, Field B- Seidou vs Komashiro
Ch 25: Seidou (2nd string) vs Asakurakita
Ch 27-36: Seidou (2nd string) vs Kokushikan
Ch 44-53: Seidou vs Osaka Kiryu
Ch 54: Seidou vs Inashiro
Ch 56-58: Seidou vs Shuuhoku
Ch 63-67: Seidou vs Maimon (Summer tournament round 2)
Ch 68-69: Seidou vs Muruta East (Round 3)
Ch 74-88: Seidou vs Akikawa (Round 4)
Ch 90-93: Ichidai vs Yakushi
Ch 97-119: Seidou vs Yakushi (Quarterfinals)
Ch 124-133: Seidou vs Sensen (Semifinals)
Ch 135-139: Inashiro vs Sakurazawa
Ch 150-191: Seidou vs Inashiro (Finals)
Ch 199-200: Inashiro vs Seihou
Ch 206-207: Seidou vs Chiba Shoudai
Ch 208-218: Seidou vs Yakushi
Ch 221: Seidou vs Toyosaki (1st round of fall tournament preliminaries)
Ch 225-226: Seidou vs Seishou
Ch 229-236: Seidou Intrasquad (1st and 2nd years vs 3rd years)
Ch 242-256: Seidou vs Teitou (Fall tournament round 1)
Ch 261-265: Seidou vs Nanamori (Round 2)
Ch 265-270: Inashiro vs Ugumori
Ch 274-290: Seidou vs Ugumori (Round 3)
Ch 301-312: Seidou vs Ouya (Quarterfinals)
Ch 313-314: Sensen vs Seiko
Ch 320-325: Seidou Team A vs Team B
Ch 329-351: Seidou vs Seiko (Semifinals)
Ch 352-361: Yakushi vs Ichidai
Ch 370-410: Seidou vs Yakushi (Finals)