Hatching Percentages and the buddy system

Morning all,

I am far enough along in this game that randomly finding Pokemon I need isn't reasonable.

The three main avenues are eggs, nests, and the buddy system. Nearest I can tell nests are absolute wild cards for quantity and duration so I wanted to focus on eggs and my buddy.

When it comes to buddy selection my thought is I should choose the Pokemon in a distance subset (1/3/5) that has the least likely chance of hatching. Examples might be clefairy, geodude, and grimer and rankedboost seems to confirm that however I dont have the highest confidence in their numbers because I cant see there work.So....

What are the odds of a specific pokemon per egg (that is: knowing what egg is being incubated) and what are the odds of a specific pokemon in any egg (that is: not knowing what egg is being incubated)?

I know that is a really big question and I imagine you are already looking into it but I haven't been able to find any good source already.