This is my idea how the M&L US/Europe boxart could look. Simple compared to the US boxarts of the previous Mario & Luigi RPGs, but there's more going on here than the Japanese boxarts for all three. Needless to say, I have high expectations for the US/Euopean boxart design. I drew Mario, Luigi, and Bowser, but copy pasta'd Fawful and the Star bob-omb thing (sorry if my knowledge on that character is limited; I'm avoiding certain details of the game until the US release.)
EDIT: updated with the official logo. I just bought my copy, and I must say I am very tempted to tape this on top of the official boxart. It's like they didn't want it to live up to the amount of activity that the boxarts of the first two had.
I do not own anything here. All subjects used (except for the rating, which belongs to ESRB) are trademarks of Nintendo. This boxart design is just fanart.