The user requires artificial/external means to regulate and stabilize their otherwise uncontrollable powers. Without these regulators, the user's powers could be a danger to themselves or those around them. Said regulators typically take the form of a technological device.
In some cases, the user performs certain tasks or techniques, such as meditation, to keep their powers under control.
Bridge Carson (Power Rangers:SPD); must wear gloves in order to prevent accidentally using powers
Marika Reimon aka Jasmine (Tokusou Sentai Dekaranger); must wear gloves in order to avoid accidentally using her powers of reading someone else's thoughts
Amata Sora (Aquarion Evol)
Lelouch Lamperouge (Code Geass)
Rei Ogami (Code: Breaker)
Z Fighters (Dragon Ball franchise); via regulating their Ki
Frieza (Dragon Ball Z); regulating his Ki via lesser forms
Evergreen (Fairy Tail)
Natsume Hyuuga (Gakuen Alice)
Kusuo Saiki (Saiki Kusuo no Psi-nan)
Sairaorg Bael (Highschool DxD)
Hina Nitta (Hinamatsuri); by constantly applying/using her powers
Kakashi Hatake (Naruto)
A-ko Magami (Project A-ko)
Moka Akayashi (Rosario + Vampire)
San Otonashi (Rosario + Vampire II)
Hiko Seijuro XIII (Rurouni Kenshin)
Fai D. Flowright (Tsubasa: Reservoir Chronicle)
Bui (Yu Yu Hakusho)
Hiei (Yu Yu Hakusho)
Bartholomew Kuma (One Piece)
Kirie Sakurame (UQ Holder); via Save Points
Deus (Asura's Wrath)
Positron (City of Heroes)
Potemkin (Guilty Gear)
Conduits (InFamous Series); must drain sources of the element they control to keep their powers ready to use
Brooke Augustine and the D.U.P.; must encase Conduits's hands or entire bodies
K' (The King of Fighters)
Riku (Kingdom Hearts)
Hazmat (Marvel Nemesis: Rise of the Imperfects)
Raiden (Metal Gear series)
Psycho Mantis (Metal Gear Solid)
Colonel Volgin (Metal Gear Solid 3: Snake Eater)
Python (Metal Gear Solid: Portable Ops)
Drahmin (Mortal Kombat)
Most T-103 series Tyrants (Resident Evil)
Shadow the Hedgehog (Sonic the Hedgehog)
Oro (Street Fighter)
Regal Bryant (Tales of Symphonia)
Jade Curtiss (Tales of the Abyss)
Blight (Batman Beyond) wears specialized synthetic skin to keep his radiation in check.
NRG (Ben 10) wears a specialized containment suit to keep his radiation in check.
Hexadecimal's (ReBoot) mask is the only thing that keeps her power in check.
Torpid (X-Men: Evolution) must wear gloves to keep from paralyzing anyone she touches.
Negative Man (DC Comics) must constantly wrap himself head-to-toe in special bandages to keep his radiation from harming others.
Raven (DC Comics) must meditate daily to keep her emotions and powers in check.
Samantha Argent of Project HK (Hunter Killer) gives off uncontrollable bio-energy emissions and can only keep her powers grounded through specially designed discharge units which double as weaponized conduits.
Black Bolt (Marvel Comics) has gone through rigorous training to control his destructive voice, and the antenna on his head helps to channel it.
Cyclops (Marvel Comics)
Havok (Marvel Comics) needs to wear a special suit to keep his powers in check to avoid accidentally hurting someone.
Jennifer Takeda/Hazmat (Marvel Comics) needs to wear a containment suit whenever she is outside of a controlled environment.