There are a few things that need to change:
1) Why is Wallace's rematch team mono-Grass?
2) If there's room in the rom, you can put held items on normal trainers.
3) Aqua Admin Matt has four Pokémon with no held items and default attacks, and an AI value of 50. Additionally, there are several 4x weaknesses on his team. He seriously needs to be buffed up...