Bulma Briefs Of Capsule Corp after the Moon was destroyed By Piccolo and was brought back decided to Help Y/n Train by Using her resources and scientific knowledge to turn the entire Moon into one Massive Gravity Training room.

The Moon was designed to go up to 500X (Absolute Shounen Jump) Earth's Gravity but can be Modified to go further if needed. The Moon was also Given an Energy Shield to protect it from any attacks that would destroy it like before so as to not ruin her Hard Work.

Of course, after Y/n found out they Both had A Discussion about the Morality of such A Thing in A Smiling Friend-styled Conversation.