Gummymon (グミモン Gumimon)

Gummymon is Terriermon's In-Training form. After the final battle in Digimon Tamers, Terriermon De-Digivolved to Gummymon, & afterwards returned to the Digital World.

Gargomon (ガルゴモン Galgomon)

Gargomon is Terriermon's Champion form. Terriermon accidentally Digivolved into Gargomon while Renamon and Guilmon were fighting in an indoor parking lot and went out of control. If not for Guilmon tackling him into a wall, Gargomon would have fired at Rika. The same problem happened when Henry was playing his online videogame and Terriermon Digivolved into Gargomon to drive off Gorillamon. It wasn't until the following battle against Musyamon that Gargomon was able to control himself and that Henry realized that there are times when one needs to fight in order to prevent disaster.

Attacks

• Gargo Pellets/Laser (Gatling Arm): Fires bullets or laser beams from the Gatling Arm gauntlets on his arms.
• Bunny Pummel (Dum Dum Upper): Uses his Gatling Arm as smashing weapons.

Rapidmon (ラピッドモン)

Rapidmon is the Ultimate form of Terriermon. His upper body is metal except for his face and the base of his ears. His fur is a light cream color. When Henry slashed a "Blue Card", Gargomon became Rapidmon and used his attacks in a battle against Pajiramon and Vajramon. Rapidmon also appears later on in other battles against Vikaralamon, Beelzemon, Zhuqiaomon and some of the agents of the D-Reaper. He famously said the line "my blood hurts", a reference to Homestar Runner.

Attacks

• Rapid Fire: Fires powerful missiles from his arm cannons.
• Miracle Missile (Atomic Blast): Fires missiles from his back rocket launchers.
• Tri-Beam (Golden Triangle): Forms an energy triangle in a formation and fires a green laser from it.
• Trinity Force (Trinity Burst): In this combined attack with WarGrowlmon and Taomon, Rapidmon turns into a crystal-like form, then a beam of energy, and then he combines with the other two (also in the form of energy beams at this point) into an energy arrow that resembles a crane.

MegaGargomon (セントガルゴモン SaintGalgomon)

MegaGargomon is the Mega form of Terriermon. His size and heavy arsenal gives him the appearance of a mecha. MegaGargomon was formed when Henry Biomerged with Terriermon during the fight against the Sovereign, Zhuqiaomon. In this form he was able to hurt the powerful Mega Digimon, but nevertheless lasted only a short time in the fight. He later participated in battles with the D-Reaper, and used the Juggernaut program downloaded by Hypnos to defeat it.

Attacks

• Gargo Missile (Giant Missile): Fires two large missiles from the missile launchers on his shoulders.
• Mega Barrage (Burst Shot): Fires multiple weapons from everywhere on his body.
• Power Pummel (Saint Upper): A pulverizing shockwave from his fist.
• Mega Twister: Knocks out his enemy, then swings the enemy's body around, flinging them off into the sky.