The guy at the start said that if I sneak through the long grass, the Pokémon here won’t notice me and won’t attack. I’ve been getting by fine waiting for the right moment to sprint past. It would be useful if I could just sneak last and not have to worry about engaging in battle though. What was the guy trying to say when he said you can sneak past Pokémon in the tall grass?
The game will automatically make you sneak when you enter grass so long as you are not moving. Move the thumb stick very slowly when you get close to the grass and you will see your character will crouch down low. This means you are in sneak mode.
Once you are sneaking, move slowly by pushing the thumb stick in the direction you want to move very gently. This will ensure you remain in sneak mode.