- Cost: 20,000
Megaguirus joins the mutants to find large amounts of energy to feed her enormous hunger.
Megaguirus has high offense and unbeatable speed. However, she doesn't gain energy normally, so she must steal the energy from crystals or other kaiju. She can 'steal' the opponent’s main projectile attack by absorbing it in a grapple.
Hold 
button: Weapon Fire (Requires Energy). After stealing an attack with her grapple move, Megaguirus can use her stored energy to fire the same projectile. The properties of this move are identical to the host, meaning that most can't knockdown an opponent unless she steals the Laser Eyes from Mechagodzilla or Mechagodzilla 2. The amazing thing about this attack, though, is that after using a bar of energy, Megaguirus can fire the beam for an indefinite amount of time as long as it wasn't her only bar of energy. On the downside, the ancient insect can not aim the beam using 
, and will have to physically move to direct the attack.
Using the Earth Defenders, play the "Enter General Gyozen" stage at London. At the city, destroy three giant light teal crystals. Once this is complete, near the end of the game, after the Atoragon is defeated, the "Wrath of Megaguirus" stage will appear at London. Select this and simply beat the monster to add it to the shop. Note: the "Enter General Gyozen" stage does not actually say "reveal a new monster"