You don't need wifi, if you know somebody who has the game as well, you can simply go to him and sent him messages with the wireless function. And you can send them all to the same person. But you can't send them quickly after eachother. You have to wait each hour before sending a new message. But I heard this can be avoided by turning your DS-clock forward an hour.pretty sneaky.

So it's not horrible at all. If you know somebody who has the game, you can unlock all extra mognet stuff in, let's say, half an hour if you can really cheat with your DS clock. Send 7 messages to a friend like:

you "Hi"
he "Hello"
you "Thanks"
he "For?"
you "Being able to let me do mognet"
he "You're welcome"
you "Thanks again"
he "It's no big deal"
you "It isn't?"
he "No"
you "Oh"
he "..."
you "Hey, we have 7 messages!"
he "Yay! Onion Knights!"

Well, I don't know how your mails look.
And, for the Ultimate Class in the game that can deal more than 9999, it would only be fair that you have to work for it.