Activating Gum Mode makes Buu tougher and denser! This changes a few things, gameplay-wise.
- At activation, you will see an empty Majin 'M' symbol (which acts as a bar/gauge) added to the screen. Its level is indicated by the color that the 'M' gets filled up with: yellow = Lv1, red = Lv2, black = Lv3.
- Power Charge is replaced by Gum Charge, which fills up his Gum Bar.
- Blocking attacks also fills up the Gum Bar.
- Buu becomes tougher, gaining armor, indicated by his exhaust of steam.
- 1 hit of armor at Level 1, 2 at Lvl2, and 3 at Lvl3.
- Getting hit still deals full damage to Buu, but he won't go into hitstun as long as he's got armor.
- After all the hits of armor have been taken away, his steam will stop and he'll go back to receving hitstun.
- The armor will be regained over time, indicated by the return of the steam exhaust.
- Gain access to the Mega Candy Beam, detailed below.
- All Supers cost 1 Power Bar meter less to perform but take you out of the mode upon activation.
- Kill You gains Finishers at the end, there being three variants (Lv1, Lv2, Lv3).

This is Buu's Gum Mode cancel move, using all of the current Gum bar and pouring it into this one attack. The Mega Candy Beam is a full-screen attack that turns the enemy into a piece of candy. The more your Gum bar was filled, the longer the enemy is forced to remain a candy. This gives you ample time to power up, taunt, take a sip of your drink or think of ways of continuing your attack!