The lyrics you're referring to is from the English version of the theme song from the original Pokemon series, called "Gotta Catch 'Em All"
Verse 1: I want to be the very best Like no one ever was To catch them is my real test To train them is my cause
Chorus: I will travel across the land Searching far and wide Each Pokemon to understand The power that's inside
Verse 2: Gotta catch 'em all, it's you and me I know it's my destiny Pokemon, oh, you're my best friend In a world we must defend
Chorus: Gotta catch 'em all, a heart so true Our courage will pull us through You teach me and I'll teach you Pokemon, gotta catch 'em all
Outro: Gotta catch 'em all, gotta catch 'em all Gotta catch 'em all, yeah!
This is the most popular version of the theme song, there are many versions of the theme song in different languages and from different series of the Pokemon franchise.