Breeding a female marowak (f:0) with the ability Battle Armor will not result in their offspring inheriting the hidden ability despite repeated trials. Furthermore, by changing the name of the ability in the stats folder to be just BattleArmor (without the u) to try fixing this results in this: https://gyazo.com/4f123358e5e5d187bd48cf08d552a037

Moved to new ticket on request from #14077.

Thanks for the report. Having done some testing with this it looks like it is the case with both Marowak and Exeggutor, for both Kantonian and Alolan forms. What these two have in common being that they both have Kantonian and Alolan forms that have Hidden Abilities, but their pre-evolutions only have one form. So this probably has something to do with the checks that prevent an Alolan parent passing down a Hidden Ability to a non-Alolan child, but is also affecting the non-Alolan parents. I've passed this information along.

Also normal Raichu can't seem to pass down Lightning Rod.