Most pokemon, when bred, produce offspring of the lowest evolution level in their line. For example, a pair of Fearows would produce Spearows. While most pokemon can reach adulthood in any of their stages, there are some exceptions to this. Bug pokemon with a larval stage (such as Caterpie) will not be able to breed until in their final evolution form. Others, such as Pichu, have set baby stages that eventually evolve into their next stage without any problems. In these cases, as the baby matures, an evolution application should be sent in to bring them to their adult stage. Generally speaking, if you've had the pokemon out and about, these will be approved without difficulty and will not require a scene.
Tyrogue operates slightly differently. Because it can evolve into one of three pokemon of various strengths, you must choose which you want it to become and RP training it accordingly. For Hitmonlee and Hitmontop, one or two logs should be sufficient. Because Hitmonchan is a more powerful pokemon because of our battle system, more logs are necessary and a scene may be required.
In the cases of pokemon that have more than one evolutionary path to follow, offspring will have a tendency to want to become what their parents were. For example, an Eevee born to two Jolteons will prefer to become a Jolteon. It is not set in stone that this is the only way they can evolve, but most will prefer to follow in their parents' footsteps.