• Get the Goddess Ribbon.
• Don't use Paralysis on Pokey.
• No Bottle Rockets of course.
• Don't prepare for anything. Be Anti-Boy Scout.
• You can get the Gutsy Bat from a certain enemy *coughBionicKrakencough*. Can you do it?
• Are you at level 60 or under? If you are, you must stay at that level and fight Giygas to complete this challenge.
• Can you kill the other characters, and beat the game only with Paula?
• Remember how we told you to leave a Shattered Man alive in the Scaraban Cultural Museum? Well, he'll be the only enemy who's still there after you beat Giygas. You can fight him with Paula and Ness, or with Ness alone. Be careful not to lose, though, as that apparently causes the game to hang.
• And the final challenge, do not enjoy the ending.

Here's an interesting change...in the VERY end of the game. It seems that NOA was not confident in making a "Mother 3". So instead they give us a sappy "The End..?". Also, you know how in you input your name twice during the game? Well, in Mother 2, you input your name in English, and the second time in Japanese. Why? The Japanese name shows up when you're praying, and the English name appears in the credits.

Thanks to Tomato for providing this Mother 2 information! Visit his Mother 2 to EarthBound and Back Again translation site for more Mother 2 to EB comparisons!