He didn't. Yo-yos have been around for over 2500 years. Ancient Greek excavations have unearthed yo-yos made of terra cotta, wood and metal.
Phillipine hunters have used yo-yos for small game and birds for 400 years. The word yo-yo itself is Tagalog for 'come, come'.
Mr. Flores' contribution is limited to marketing in the US only, during the 1960s.