We used to think that Nintendo's programming was above reproach, when, in reality, Nintendo's work -- even EAD's top-shelf games -- are just as riddled with bugs and glitches as anyone else's. And that's to our benefit, since without Nintendo's occasional gaffes, there'd be no Minus World, no secret Metroid maps, and no Chris Houlihan's Room (or no way to get there, anyway).
In the case of Zelda II, you can use a weird glitch to give yourself an advantage early in the game, provided you can get through, uh, the early part of the game. First, complete a palace level. Pause the game, save, and quit while the experience points are tallying (using the in-game save system, not the Wii's). Open a game in another profile. The experience points will be added to this player's profile instead of the first. Completing any of the later palaces would send multiple levels' worth of points into a new game.
As we mentioned, the catch is that you have to be able to complete palaces before you can benefit from this. The difficulty of the freaking palaces is what makes this glitch worth exploiting in the first place.