Frankly, in the main series games, Baby Pokemon are an underdeveloped concept. There is really only one thing that is universal between all Baby Pokemon -- they are not able to produce offspring under any circumstances. Most of them were added in a later generation to expand an evo-chain, except Togepi and Riolu.
Some Baby Pokemon can only be obtained by breeding with a specific Incense. In order to obtain the Baby, the mother must be holding the corresponding Incense in order to produce the Baby. This can cause some complications when performing competitive breeding, as you have to give up either the Destiny Knot (passing IVs) or the Everstone (passing Nature) in order to hold the Incense.
A final note is that sometimes the Baby will have different Egg Moves than the rest of the evo-chain.