If we take the anime's word for it and say Ash has been 10 years old through out his entire journey then if we look at his career as a trainer from a real life perspective then he'd be a prodigy.
>reaching top 16 in his first regional tournament
>becoming champion in an albeit much much less competitive region
>reaching top 8 twice in a row during his next two regionals
>conquering the battle frontier
>reaching top 4 in his 4th regional
>under performing in his 5th regional only reaching top 8
>being runner up in his 6th regional
>becoming the first champion in Alola's first official tournament of the region