Hiploop is the Japanese name for the more commonly found Zelda enemy known as Helmasaur. However, in Majora's Mask, the enemy did not receive the same name translation and instead retained the name Hiploop. In Four Swords, the Hiploop is identical to The Minish Cap counterpart, however, it was given the name Hiploop instead of Helmasaur. The face on these small creatures are its weakspot, however, they are protected by a mask that can be pulled off.
Hiploops are hotheaded,
In Majora's Mask, Hiploops are larger insect-like enemies and only some of them can be seen wearing protective masks. They are first encountered in Woodfall, just outside the entrance to the Woodfall Temple. They appear on narrow platforms and charges at Link, trying to knock him off the ledge. Link can defeat them while in Deku Link form by first stunning them with a Spin Attack, and then using a Bubble Blast to finish off the enemy.
Alternatively, if Link is in Hylian form, he can use his Shield to deflect the Hiploop back when it charges, then allowing time for a counter-attack with his sword.
When Link later encounters the Hiploop within the Stone Tower Temple, it now has its large metal blue mask. Link can remove this mask by using the Hookshot, Bombs, or the Blast Mask. At this point, the enemy can be defeated quite easily.
In Four Swords, the Hiploop are the identical enemy as the Helmasaur from The Minish Cap. They are small red creatures with an iron mask that charges at Link when they see him. In Four Swords, Link can remove their mask by using the Magnetic Gloves, making the enemies helpless to almost any single attack. While it is much more difficult, Link can defeat a Hiploop before his mask is removed by attacking the enemy from its backside.