Well when I played Beyblade(a long time ago), I thought beyblade was just based on luck, but now I see theres customizations and such, do they really affect the performance of a beyblade?
I was thinking of getting a Storm Pegasus.
Customization is crucial in Beyblade if you want to be a good player. It mixes different parts from other Beyblades together to create the ideal Beyblade for a particular situation. Combos are built based on what Beyblade your opponent is using, the stadium being used, etc.
Read around the site, and the Beywiki (which ♥ already gave you a link to) and you'll get a better understanding of customization and why it's important.