Just a heads-up to anyone who hasn't bought Pokémon Conquest and is considering it - the downloadable events are only available until the end of the year, meaning you're going to pass up on some interesting stuff if you don't hurry up!
The clincher is arguably the mighty Reshiram, definitely the easiest legendary to obtain as long as you downloaded it. Access to Motonari and Motochika in the main story is also compelling, since they are the only warlords of their respective types among those obtainable in the main story (sure, you can also use generic warriors, but warlords have much better stats, and getting a head start on evolving their Pokémon and potentially themselves will be very helpful for the special episodes). There's also the three downloadable episodes, where your interest in them entirely depends on your completionist tendencies - there are six episodes that are the same as Okuni's, six others are the same as Ranmaru's, and three others are the same as Keiji's. Although the last one may have a certain appeal, since Keiji doesn't appear in a lot of episodes, whereas Okuni and Ranmaru are obtainable in a vast majority.
Something to keep in mind, so make yours up quickly!