Hi Erupi! I notice that you've changed my edit aboutBattleship Ru-Class. I'm pretty sure that she can be found in 3-4 map. I'm currently having trouble clearing that map because of her. You can check out World 3 to make sure.
Anyway, please reply me if I'm wrong and have a good day, Teitoku ^v^
I'm not sure if you're mistaken then info on the trivia or not. The trivia is for: "Ru-kai Battleship", the Brock Lesnar on overdose steriod version of Battleship, which isn't shown in any other normal map than 4-5 and 6-2.