Speaking of Nene, now I see why people are saying Pokemon Conquest reuses character designs from another game, Samurai Warriors. Those must be pictures from Samurai Warriors- the outfits for Nene and Hanbei are very recognizable. Though I'm not sure which game is Samurai Warriors itself; the title is very generic. The rest of the pictures could be passed off as historical portraits. In fact, that picture of Nobunaga looks like it came from the mainline Nobunaga's Amibition series.
For comparison purposes:
http://www.pokemonconquest.com/en-us/character/nene