Megontas are enemies from the Kid Icarus series.
In Super Smash Bros. 3DS/Wii U
Megontas appear as enemies in Smash Run. Their shells protect them from attacks and can only be harmed if an attack hits their stomach. To knock over a Megonta, a player must deal a strong attack to the stomach; either a Smash or a powerful Down Tilt is enough to flip one over. Once they are flipped over, they will attempt to recover themselves which during this time they are unable to attack.
Megontas have two attacks; their roll attack and a projectile attack. The roll attack starts when the Megonta jumps and spins before ramming into the direction the player was. The attack breaks shields instantly and does decent knockback. If they cannot reach the player, they will launch a projectile which does large explosive damage and knockback.
You wouldn't think a wood louse would make a very scary enemy, but when it's as big as this... Eek. It attacks by curling into a ball and rolling across the stage. There's no point in hitting its shell--it's solid. Instead, knock it onto its back with a smash attack, and then pummel its stomach while it's trying to right itself.