How does the size of the pokemon: XL, L S etc. affect its ability to battle?

If u have a pokemon that is overall is in the 66-80% range. But yet its the tiniest on record. Do I need to look for one that has the same stats but bigger? Or does size affect its battling ability at all?

If u have a pokemon that is overall is in the 66-80% range. But yet its the tiniest on record. Do I need to look for one that has the same stats but bigger? Or does size affect its battling ability at all?

If u have a pokemon that is overall is in the 66-80% range. But yet its the tiniest on record. Do I need to look for one that has the same stats but bigger? Or does size affect its battling ability at all?