You will need

0-6 months (16in Chest) - 2 Balls
6-12 months (18in Chest) - 2 Balls
1-2 years (20in Chest) - 3 Balls
2-3 years (22in Chest) - 4 Balls

3.25mm and 4mm Needles
Stitch Holders
5 (6 : 6 : 6) Buttons for Round Neck Cardigan
4 (5 : 5 : 5) Buttons for V Neck Cardigan