The Alliance Borderers is a canon unit but as long I am using custom vehicles, I understand it becomes non-canon so I need to post it here.
This is a full regiment armed only with combat vehicles. As long the OA keeps good relations with the Draconis Combine and the Federated Suns, the main use is against pirates raids. I see them as mobile combat unit, able to defend and counter-attack small enemy formations. Sometimes they will defend the world they are based, other times they will be deployed in another planet to deal with pirates that landed there and are fighting the local OA planetary militia which normally holds the ground until reinforcements arrive (in this case, the Alliance Borderers).
The three companies are listed here:
https://owa3025.blogspot.com/2021/05/unit-profiles-alliance-borderers.htmlEach one have a first company with heavier vehicles for defense that are deployed in worlds with more strategic assets, like weapons industries. The 2nd Battalion is an exception because it is based in a world that covers others that are frequently under pirate attack like Dneiper and Milligan's World, so the first company has hovercrafts, mainly Condors.
The second company uses Vedettes and Hunters that are produced in the OA with good mobility and average firepower. They should be able to hunt faster mechs and vehicles but can't deal alone with heavier mechs.
The third company is made of custom VTOLs armed with autocannons and LRMs. They can be used to flank enemy formations and deal even with heavier mechs fighting alongside the land combat vehicles. Pirates may eventually be armed with flak ammo but are most of the times not well prepared to fight heavily armed VTOLs.
No infantry is provided and they need to operate alongside the local militia of each planet to have infantry support.
You can find links to the custom units in the page above.
