is green poop normal for a newborn
Your baby’s first bowel movement will be black or greenish black and look like tar. It will be really sticky too. This is called meconium. Most babies start to pass meconium within 12 hours of their birth.
There is a lot of variability in normal poop colors, and green is within that range. Oversupply can cause green poops, but it's only a real concern when it is accompanied by excessive gas and discomfort. You can keep offering one breast for an entire feed, switching sides for the next feed, if your baby seems content with that. If it is a touch of oversupply causing the green poop, then doing that will probably be enough to get your milk supply to sync up with your baby's needs; it can just take a little time for that to happen.