If Hideyoshi and Mitsuhide are on opposing sides during a banner battle (like in Viperia), the two have a special exchange of dialogue:
Hideyoshi: "We can't lose to Mitsuhide! We've got to get those banners first,(Pokemon)!"
Mitsuhide: "We shall not be defeated. Come, (Pokemon)."
This is likely a reference to the Battle of Yamazaki, in which the real life Akechi Mitsuhide and Toyotomi Hideyoshi fought against each other, after Mitsuhide had betrayed and murdered Oda Nobunaga.

Hanbei has the lowest Power stat of any Warlord, likely a reference to the real life Takenaka "Hanbei" Shigeharu, who suffered from tuberculosis, dying young because of the disease. In the ending of Hanbei's story, Spoiler:he even sounds like he may be sick.

Hideyoshi's perfect link with Chimchar, Monferno, and Infernape is a historical reference; the real-life Toyotomi Hideyoshi was often called "Saru", the Japanese word for "monkey", because he was said to have the physical features of one.