Mammoshka

Mammoshka is a boss in Mario & Luigi: Dream Team. Found near the top of Mount Pajamaja, this mammoth-like creature acts as a guardian for the mountain, and is battled by Mario and Luigi in their journey to the mountain's summit. Its name is a pun on Mammoth and Babushka, also known as the Matryoshka.

Appearance
Mammoshka appears to be a mammoth-like creature inside an igloo-like armored shell.

History
As Mario and Luigi were climbing the summit, a single Pi'illo rescued on the mountain talked of a "guardian" found in the region that would prevent intruders from reaching the top. After that though, the Mario Bros. didn't see or hear any sign of Mammoshka until they reached an area near the top of the mountain where they found it sleeping.

With the guardian in sight, the Massif Bros. managed to sneak around it, leaving the Mario Bros. to do the same. Unfortunately, Luigi just happened to sneeze at the wrong time, waking up Mammoshka and forcing the Bros. to defeat it in battle.

After it was defeated, Mammoshka was never seen again in the storyline.

Battle
In battle, Mammoshka has quite a few different attacks to use, as well as unique battle ending animation afterwards. Its first attack is to shove a giant snowball at either Mario or Luigi, who have to hit it to the other character. After a few hits with the hammer (with the snowball gradually getting smaller) it'll be launched back at Mammoshka, but if a character gets hit by it, they'll then be caught on the snowball and sent flying off screen, where they need to press either or  to jump and break free.

It can also go into the background and throw a large rock towards Mario and Luigi, forcing them to hammer it back at Mammoshka with their hammers.

Mammoshka can also chase Mario or Luigi towards the other character. If they jump over the other Bro. they'll avoid taking damage, if they hit them they'll both get trampled by Mammoshka.

Another attack it has is to chase Mario and Luigi down the mountain, trying to suck them into its trunk. If Mario and Luigi dodge its attacks, it'll eventually end the chase, but if one brother is sucked in, it'll then be shot out towards the one remaining, who has to then jump over them as they fly down the screen.

Part way through the battle, some Monolifts that aid Mammoshka appear. These enemies seem to be carrying helmet like objects inside blocks on their heads, and if they're not defeated, will give Mammoshka a spiked helmet to protect it from Mario and Luigi's jump based attacks.

Finally, at the end of the battle, Mammoshka's armor will start to crack, revealing a smaller version of it underneath. Mario and Luigi then chase it down the mountain, until eventually the "true" form of the creature is revealed. After one last jump to its head from Mario or Luigi, Mammoshka is defeated.

Trivia

 * Mammoska and Trunkle are both similar in the way that they can both be found sleeping and guard a path leading to a high altitude area.