I want a Shiny Charmander but I can't get one, so I asked this question, I used the Masuda method (with an Inglish ditto and a Spanish Charizard (my game is in Spanish btw)) and I can't afford to get a Shiny charm, so of there is a way to Increase the odds without the 2 mentioned Thing before PD: the game is Sword if you ask
If you can't get the shiny charm, you are doing everything that you can otherwise by using different regions. Your odds are 1/683 without the Shiny Charm, which is better than most other shiny hunting methods. Good luck!