The Mushroom Up's normal attack is either a butt with its head that can hit everyone in melee range or lashes with its tentacles that can strike for several hits. Its most dangerous Special Attack is One Hundred Lashes, a lashing attack that can hit everyone for a number of strong hits at melee range. Entangle is a squeezing attack on a single target. Finally, if it puffs up at the end of its turn, then it will begin its next turn with Poison Scatter. This attack damages everyone in range and would theoretically cause Poison status, except that everyone in the party is either already under Poison status or immune to it while within the Woodblock Groves. If the character or characters it targets with this attack are far enough away, then it will simply do zero damage.
Like other opponents of this class, the main challenge in the PlayStation 3 with it is that it has relatively high HP compared to the other opponents in the area. None of its attacks are really all that damaging, even if a Guard is missed. The Poison Scatter attack can even be avoided by simply moving all characters away prior to the start of its turn. Since it has no distance attacks, using Viola as a distance attacker while everyone else attacks at close range is an excellent choice. It is generally recommended to build up Echoes and then unleash a powerful Special Attack to wear down its high HP. They will often group together to attack targets at melee range, which makes it incredibly easy in turn to strike more than one of them at once and swiftly build Echoes, particularly with Jazz.
In the Xbox 360 version, however, with its particularly low HP and no real defense, it is little more than a joke monster. If caught from behind, the entire field of monsters can easily be defeated in one turn. Even if not caught in a back attack, they will still quickly fall.
In Encore Mode, they possess greater HP and the attacks can prove a slight challenge, but the party has new powers at their disposal. A Harmony Chain begun at 32 Echoes with a total of six Special Attacks used will make especially short work of their high HP. If anyone needs healing, Viola's Heal Arrow is a powerful resource and if healing isn't needed, then her Hawk Eye is recommended to mark these targets for additional damage and highly powered Special Attacks. In the PlayStation 3 version in particular, Viola can finish these targets off in one turn at a distance once they are marked for damage with Hawk Eye. In Xbox 360, they remain at best a minor threat.
- In the PlayStation 3 version of Eternal Sonata, the Mushroom Ups are replaced with two Red Caps in the battle with Trick or Treat. These have the same appearance as the Mushroom Up and use the same attack set, but have substantially greater HP.
- Curiously, in the Xbox 360 version, when a Mushroom Up is defeated, it will appear fallen like a KOed character, rather than simply disappearing from the screen like most defeated opponents.
- The Poison Scatter attack is intended to cause Poison status, as if a character is wearing an armor or accessory that protects against Poison or all status ailments, then the game will indicate that the character resisted the poison. This, however, is academic, since if the character did not have the armor or accessory equipped, they would be under a continuous poison status anyway.
- In the PlayStation 3 version, after collecting the Scrapbook, there is a picture titled "Tricked!" with the Mushroom Ups chasing Allegretto.