This can be a tricky one to fix, because the TransN of the new model MUST be in the same spot as the replaced model. Example: you want to replace Mario, he has a TransN of 7, therefore to avoid the walking glitch the new models 7th bone must also be TransN. The easiest way to fix it is to find a character that has the same TransN index and replace that one. If you can’t or don’t want to replace those characters, then you can either rename the bone that is in the TransN index of the replaced character, but this might cause issues later on, because Brawl is referencing a random bone thinking it’s the TransN when it really isn’t.