On second thought, it should be right. The first Pokémon that actually appeared was Mamanbou(something like that), but I guess you can say Zekrom or Reshiram.
Although my second question hasn't been answered, here is another one.
This legendary Pokémon is actually NO.000 on the Isshu Déx, right before Tsutarja(which is the one I'm getting because it looks like Yoshi!)