Arthur the Artist shows us how he transforms into 1930's cartoon style using his magical paintbrush, unlike how Brenden uses a syringe to also turn into that style. And if you're wondering why Arthur has a French accent, that's because in my universe (and probably in Elementcats' universe too), the Alphabest Friends have their voices based on their personalities. For example, Yang speaks with a Chinese accent.
Credit to all, especially @NooalfFan35 for Arthur the Artist.