From the Super Mario Wiki, the Mario encyclopedia
The Training Machine is an item from Super Paper Mario. It is a 2-screened handheld that resembles a Nintendo DS. Mario and co. received it from Bestovius to deliver to Merluvlee, after giving Bestovius the You-Know-What. Upon giving it to Merluvlee, Mario and friends question which body part Merluvlee would use it to train and Merluvlee cheerfully replies that she trains her brain, which is a reference to Brain Age. Apparently, the Training Machine is an old model; Bestovius claims to have a newer, slimmer version (likely a reference to the Nintendo DS Lite). This is used in the Piccolo side quest. In return, Merluvlee gives a Crystal Ball to give to Merlee. Giving this to her will gain the player a key to a house in Flopside where Piccolo is trapped.
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