After having a baby can you get a flat stomach again without a tummy tuck?

Possibly. There are many variables involved when it comes to the appearance of the abdominal wall women will “achieve” after pregnancy. Generally, it is possible to achieve a flat abdominal wall without surgery for some patients; for others, despite best efforts, issues such as abdominal wall laxity and/or loss of skin elasticity, do not allow for ideal aesthetics without tummy tuck surgery.
Possible. Yes and I have seen this. However there is no sure fire method to assure this possibility as there certainly is a large genetic component which effects skin elasticity and striae formation as well as development of a diastase. The weight gain during pregnancy and size of the child may also have an effect. Exercise during pregnancy and return to core strengthening regimens have been suggested.
Yes. It is very important that you begin the process prior to pregnancy if possible. Eating high protein, moderate carb, low fat diet with prenatal care...Coupled with quality abdominal exercises to maintain maximal tone is critical. Early return to isolation exercises for tummy will greatly improve the return to pre-pregnancy tone and contours. Takes work, but worth it.
Sure.... Some women are able to do this. Not every woman will come to have a tummy tuck.
Get back in shape. It is possible to get your shape back after a baby. Breastfeeding, regular diet and exercise will help. Good core work outs will help you regain your shape. However, it may take longer if you are older and this is not your first child.