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Methods
Stationary: Method 1.
Wild: Method H-1.
Note: You might encounter Vblank issues with wild Pokémon, resulting in Method H-2 or H-4, but this is a rare occurrence.
Intro
Ruby and Sapphire may have fewer tips than FRLG or Emerald due to the Live Battery method, but there are still valuable insights to share.
Trainer Card Flip
In Gen 3, flipping your Trainer Card resets noise-related delays, helping you focus on the default delay. It's important to do this reflexively. Access your Trainer Card and press A. Try to do this between 10k-5k advances before your target advance. This can save you trouble.
Minimizing Noise
To reduce vblank and noise issues, open your Trainer Card at the start of your RNG, perform a flip, close it, and then advance to your target. This simple strategy can protect you from unexpected surprises.
Speeding Up RNG Advances
Ruby and Sapphire have limited options for speeding up RNG advances compared to Emerald, Fire Red, or Leaf Green. However, like any Gen 3 game, being in a battle doubles the RNG advancement speed, which is useful for wild Pokémon RNG.
Painting RNG
Although it's not very useful for Live Battery, the Painting method does work in Ruby and Sapphire. As it's more advanced, it will be covered in a separate guide.