The addition of Rare Mammott marks the introduction of the game’s first Rare Monster that consists of a single element. On July 6, 2015, with the introduction of Rare Single Elemental version 1.3.4, it was finally implemented. In its rare form, this Monster has limited availability. You can get one from the StarShop when it’s not available by breeding two Monsters with the Cold element into a triple-element Monster. The default breeding time is 6 hours. Despite being a Rare Monster, Rare Mammott does not generate a lot of currency.
In addition to the above, it can be bred in the wild between a standard Mammott and a Shugabush on Shugabush Island. Nonetheless, it could be less difficult to breed a second Rare Mammott on another island and then transport it to Shugabush Island (after feeding it to Level 15). This is because both the Shugarock and the Shugabush, which can be produced by the Shugabush Island combination, need a long time to breed and to hatch their young. Also, for double the Starpower, you can purchase a Rare Mammott from the StarShop.
It is not recommended to breed a Clamble and Bowgart in Plant Island, as this is the same combination as a Shugabush, which requires a very lengthy time to get through the Breeding Structure and the Nursery, just as it is not recommended to breed a Mammott and Shugabush in Shugabush Island. Yool’s mix of Congle and Thumpies makes them less than ideal for use on Cold Island during the Festival of Yay. Also, if you want to avoid getting a Punkleton during Spooktacle, don’t employ the Bowgart + T-Rox combo. Since Woolabee and Congle are Cherubble’s finest combination, you shouldn’t use them on Fire Oasis, either.