Is it necessary or better to give toddler after 12 month a toddler formula milk. if he doesn't have difficulty or picky from eating solid food.?

No: After age one it is ok to range to regular milk, almond, rice. Hemp or even coconut milk. Children do not need more than 16 oz of milk a day after age one. If your child is a good eater then the toddler formula is not necessary or better than a regular diet.

Well balanced diet: If he is growing and developing normally, it is not necessary to supplement with Toddler Formula. A healthy well balanced diet including milk are suggested.

Limit whole milk +: milk products to 16-21 oz./day; give milk in an open-mouth cup with meals. Juice is not needed. Don't allow him to sip off & on ad-lib from a bottle or Sippy cup, Wean from bottle as close to a year as possible. Brush his teeth after he eats & before he sleeps. His 1st visit to a pediatric dentist should be at a year. He can self-feed with a spoon at 15 mos. Other "milks" don't have calcium.