Can a leader with fewer then 10 wounds fill the role of a commander, or can it only be a sub-commander? I can't tell from the information in section 26.
Yes. Commander can be a Hero with any number of wounds. It just make a difference so you can add Behemoth Leaders into battalions.
Yes, seems like the distintion is the other way around to prevent stuff like 3 monsters/heroes filling a command entourage or warlord battalion
Do a stegadon in Thunderlezard can be in a battalion for behemots ? Because he is a battleline but he gains also +2 wound I am thinking at Alpha Beast the Ghur battalion
So according to the new core rules: 25.5.1 CONDITIONAL BATTLEFIELD ROLES Sometimes, the Notes column on a Pitched Battle profile will tell you to change the battlefield role of units of that type if certain conditions are met. For example, choosing a certain model to be your general can mean the battlefield role of certain units changes to Battleline. Where this is the case, unless noted otherwise, the unit loses all of the battlefield roles in the Battlefield Role column of its Pitched Battle profile and just has the battlefield role specified in the Notes column instead. It means youre Stegadons are Troops in Thunder Lizard when it comes to battalions.