>Beginning from Hoenn onward, every time Ash and Pikachu enter a new region, Pikachu has been exposed to high levels of electricity or magnetism, before or after arrival, and loses control of its own electricity, becomes confused, and runs away, forcing Ash to chase after it. This could explain why Pikachu's strength is "reset" each time they start a new reigon.
No one knows
//Jofly Hope this helps
