| Oct 19, 2025 | Koudounis | 1–0 | Dudognon | Round 1: Koudounis, Vasileios - Dudognon, Thibault | Grünfeld Defense: Three Knights Variation, Burille Variation | |
| Jul 3, 2025 | Koudounis | 0–1 | Karamichos | Round 6: Koudounis, Vasileios - Karamichos, Michail | Slav Defense: Schlechter Variation | |
| Jul 3, 2025 | Hartofylakas | 1–0 | Koudounis | Round 4: Hartofylakas, Spyros - Koudounis, Vasileios | French Defense: Advance Variation, Euwe Variation | |
| Jul 3, 2025 | Koudounis | 0–1 | Christodoulou | Round 3: Koudounis, Vasileios - Christodoulou, Panagiotis | King's Indian Attack | |
| Jul 3, 2025 | Koudounis | ½–½ | Frendzas | Round 2: Koudounis, Vasileios - Frendzas, Panayotis | Queen's Gambit Declined: Modern Variation | |
| May 18, 2025 | Ntirlis | 0–1 | Koudounis | Finals: Ntirlis, Nikolaos - Koudounis, Vasileios | Yusupov-Rubinstein System | |
| May 17, 2025 | Kesidis | 1–0 | Koudounis | Semifinals: Kesidis, Odyseas - Koudounis, Vasileios | French Defense: Advance Variation, Paulsen Attack | |
| Mar 16, 2025 | Koudounis | 1–0 | Angelakopoulou | Round 1: Koudounis, Vasileios - Angelakopoulou, Ioanna | ? | |
| Mar 16, 2025 | Koudounis | 1–0 | Mantazis | Round 3: Koudounis, Vasileios - Mantazis, Georgios Rafail | ? | |
| Mar 16, 2025 | Koudounis | 0–1 | Kouskoutis | Round 6: Koudounis, Vasileios - Kouskoutis, Georgios-Alexandros | ? | |
| Mar 16, 2025 | Papakonstantinou | 1–0 | Koudounis | Round 2: Papakonstantinou, Dimitrios - Koudounis, Vasileios | ? | |
| Mar 16, 2025 | Doudoulakakis | 0–1 | Koudounis | Round 4: Doudoulakakis, Ioannis - Koudounis, Vasileios | ? | |
| Mar 16, 2025 | Giannoulakis | 1–0 | Koudounis | Round 5: Giannoulakis, Lampros - Koudounis, Vasileios | ? | |
| Mar 16, 2025 | Gerasopoulos | 0–1 | Koudounis | Round 7: Gerasopoulos, Nikolaos - Koudounis, Vasileios | ? | |
| Dec 21, 2024 | Lacasa Diaz | 1–0 | Koudounis | XI Sunway Sitges International Chess Festival 2024 - Group A | English Opening: Agincourt Defense | |
| Dec 18, 2024 | Koudounis | 0–1 | Wang | XI Sunway Sitges International Chess Festival 2024 - Group A | Torre Attack: Fianchetto Defense | |
| Dec 16, 2024 | Isanzhulov | 1–0 | Koudounis | XI Sunway Sitges International Chess Festival 2024 - Group A | French Defense: Classical Variation, Steinitz Variation | |
| Dec 13, 2024 | Koudounis | * | Gormally | XI Sunway Sitges International Chess Festival 2024 - Group A | Nimzo-Indian Defense: Normal Variation | |
| Jul 15, 2024 | Bhattacharyya Soham | 1–0 | Koudounis | Round 1: Bhattacharyya Soham - Koudounis, Vasileios | Queen's Pawn Game: Accelerated London System | |
| Jul 10, 2024 | Trimitzios | ½–½ | Koudounis | Greek League 2024 | Zukertort Opening: Reversed Grünfeld | |
| Jul 7, 2024 | Koudounis | ½–½ | Frendzas | Greek League 2024 | Tarrasch Defense: Two Knights Variation | |
| Jul 6, 2024 | Stoumbos | 1–0 | Koudounis | Greek League 2024 | French Defense: Classical Variation, Burn Variation, Morozevich Line | |
| Jul 4, 2024 | Kotronias | 1–0 | Koudounis | Greek League 2024 | French Defense: Steinitz Variation | |
| Mar 31, 2024 | Tzagarakis | 0–1 | Koudounis | Round 2: Tzagarakis, Panagiotis - Koudounis, Vasileios | French Defense: Exchange Variation, Svenonius Variation | |
| Mar 30, 2024 | Koudounis | ½–½ | Georgiadis | Round 1: Koudounis, Vasileios - Georgiadis, Athanasios Kat | King's Indian Defense: Makogonov Variation | |
| Aug 15, 2022 | Koudounis | * | Samakas | National Greek Team Championship | ? | |
| Jul 24, 2022 | Kazantzoglou | 1–0 | Koudounis | 15th Paleochora Open | ? | |
| Jul 23, 2022 | Milonakis | * | Koudounis | 15th Paleochora Open | ? | |
| Jul 22, 2022 | Koudounis | * | Kouskoutis | 15th Paleochora Open | ? | |
| Jul 20, 2022 | Koudounis | * | Georgiou | 15th Paleochora Open | ? | |
| Jul 19, 2022 | Santiago | 0–1 | Koudounis | 15th Paleochora Open | ? | |
| Jul 18, 2022 | Khayrullin | 1–0 | Koudounis | 15th Paleochora Open | ? | |
| Jul 17, 2022 | Koudounis | 1–0 | Zwardon | 15th Paleochora Open | Catalan Opening: Open Defense | |
| Jan 4, 2022 | Iwanczuk | ½–½ | Koudounis | Cracovia 2021 B | Sicilian Defense: Taimanov Variation, Bastrikov Variation, English Attack | |
| Jan 2, 2022 | Koudounis | ½–½ | Zarnowski | Cracovia 2021 B | Queen's Indian Accelerated | |
| Jan 2, 2022 | Panek | 1–0 | Koudounis | Cracovia 2021 B | French Defense: Advance Variation, Euwe Variation | |
| Dec 30, 2021 | Koudounis | 0–1 | Cichon | Cracovia 2021 B | Nimzo-Indian Defense: Sämisch Variation | |
| Dec 28, 2021 | Koudounis | 0–1 | Szczurek | Cracovia 2021 B | Old Indian Defense: Normal Variation | |
| Aug 8, 2021 | Koudounis | * | Bardis | 30th OPEN Chess International Tournament | ? | |
| Aug 6, 2021 | Andronescu | * | Koudounis | 30th OPEN Chess International Tournament | ? | |
| Aug 5, 2021 | Poulos | * | Koudounis | 30th OPEN Chess International Tournament | ? | |
| Aug 4, 2021 | Koudounis | * | Tsaknakis | 30th OPEN Chess International Tournament | ? | |
| Aug 3, 2021 | Klimentov | * | Koudounis | 30th OPEN Chess International Tournament | ? | |
| Aug 2, 2021 | Koudounis | * | Sirigos | 30th OPEN Chess International Tournament | ? | |
| Aug 2, 2021 | Stefan | * | Koudounis | 30th OPEN Chess International Tournament | ? | |
| Aug 1, 2021 | Koudounis | * | Patrelakis | 30th OPEN Chess International Tournament | ? | |
| Jul 29, 2021 | Koudounis | * | Malassagne | 14th Paleochora International Tournament | ? | |
| Jul 27, 2021 | Platsaki | * | Koudounis | 13th International Tournament of Paleochora | ? | |
| Jul 26, 2021 | Tsapaki | * | Koudounis | 14th Paleochora International Tournament | ? | |
| Jul 26, 2021 | Tsapaki | * | Koudounis | 13th International Tournament of Paleochora | ? | |
| Jul 24, 2021 | Koudounis | ½–½ | Markidis | 14th Paleochora International Chess Tournament 2021 | ? | |
| Jul 24, 2021 | Kouskoutis | * | Koudounis | 13th International Tournament of Paleochora | ? | |
| — | Koudounis | 1–0 | Lirindzakis | National Greek Team Championship | Catalan Opening: Open Defense | |
| — | Mitsis | 1–0 | Koudounis | National Greek Team Championship | Slav Defense: Quiet Variation | |
