The different methods for wild encounters are caused by vblank, though H-2 is the most commonly seen.
Painting RNG
Painting RNG is a great method to obtain any desired initial seed. It's a more advanced technique and is covered in this guide.
Speeding Up RNG Advances
Battle Video
This method helps with seeding by preserving the RNG's state as an initial seed. Engage in a battle at the Battle Frontier and save it as a video. The video retains the seed from the battle, allowing you to set it as the initial seed when loading. For example, if your target is 1 million advances away, go up to 950k, save a battle video, and upon loading, you'll start at 950k advances.While this method is helpful, it's a bit outdated compared to Painting RNG. However, it's useful when you need to hit a specific advance multiple times.
In-Battle
Being in battle advances RNG twice as fast. This is particularly helpful for wild Pokemon RNG.