I just discovered the event passwords and decided to put them in while I was at the computer. I'm in Ieyasu's story right now. Keiji's and Okuni's worked fine, I had Motonari/Motochika and Ranmaru already from Wi-Fi... But then I put in the Reshiram code, and didn't get a message at the title screen like the others. However, it did accept the password.
If I finish Ieyasu's story and go play Hideyoshi's again, will Reshiram appear like normal? Or did I screw myself by inputting it in another story?
I haven't actually checked the "Select Story" screen to see if they're there, but I got the message on the title screen in the same way the Ranmaru one (which I got through the official Wi-Fi event) appeared.