Use Unity Asset Bundle Extractor Avalonia to dump the raw files. Then you can edit them using any text editor and import them as raw files using UABEA. Use this list to determine the IDs of the trainers: BDSP Trainer Data - Google Sheets
You can look up move, nature and ability IDs on Bulbapedia.
Toxic is unavailable for Articuno in BDSP.
The only way for it to learn Toxic was a TM in Gen 1 - 7 which doesn't exist in BDSP and there's no way to transfer mons to these games yet.