In Pokemon Conquest for the DS, once you get to a certain point in the game, you will be able to recruit (aka link) pokemon that you encounter in the wild and add them to one of your Warlords.
After you have your fifth kingdom (around the point in the story when you capture the Violight kingdom), a man by the name of Keiji will speak to you about linking to new pokemon in the wild. After this happens, you will be able to link wild pokemon for you and your other Warlords to fight with.
You’ll notice that when you encounter wild pokemon with a Warlord, each pokemon on the field will have a colored symbol above its head.
Gold – Best link possible
Silver – Good link
Bronze – Decent link
Red X – Can’t link at all
Once you see a pokemon that you can link to, move that Warlords pokemon up to it and you’ll see a new option that says Link. Once you try to initiate a link, you will be presented with a short mini-game that is similar to Rock Band or Guitar Hero if you’ve played those games, where you have to press the A button at the right time a set amount of times in order to successfully link the pokemon.
If you are successful, that pokemon will be removed from the battle field and will be linked to that Warlord if you successfully complete the rest of the battle.