Go to 'Island 2' and go to the bragget house where he asks you what you want to Brag about:

Effect - Code

Egg Hatching Sticker 4th Lv - Hatch 300 Eggs.
Egg Hatching Sticker 3rd Lv - Hatch 200 Eggs.
Egg Hatching Sticker 2nd Lv - Hatch 100 Eggs.
Egg Hatching Sticker 1st Lv - Hatch 1 Egg.
Hall of Fame Sticker 4th Lv - Beat the Elite Four, 200 times.
Hall of Fame Sticker 3rd Lv - Beat the Elite Four, 100 times.
Hall of Fame Sticker 2nd Lv - Beat the Elite Four, 40 times.
Hall of Fame Sticker 1st Lv - Beat the Elite Four, 1 time.
Multibattle Link Win Sticker 1st Lv - Win 1 Battle.
Multibattle Link Win Sticker 2nd Lv - Win 20 Battles.
Multibattle Link Win Sticker 3rd Lv - Win 50 Battles.
Multibattle Link Win Sticker 4th Lv - Win 100 Battles.