Help with HGSS Trainer Backsprite in Wild Battles

[Pikappa93]

As the title says. I managed to replace Ethan's backsprite with one created by me (I used Tinke). It works just fine, except when I enter a wild Pokémon battle in the grass: there is still one frame that uses the original sprite from the vanilla game. I've searched everywhere for that sprite to replace it, but no luck. Anyone has any idea on how to fix this?