The power of Gluttony has two steps: by eating the victim's "name" they can erase their existence from the rest of the world, and no one will remember who you are; by eating the victim's "memory" the victim loses memory of who they are. If both "name" and "memory" are eaten, the victim also goes into a coma.
In act 3 Cruche has had her memory eaten, and in act 5 Julius had his name eaten. Rem had both her name and memory eaten and now is a comatose with no one remembering who she is.
Regulus Cornius, Bishop of Greed - Obnoxious, whiny, and arrogant, Regulus never shuts up. He constantly justifies his own action and complains about everyone else's. He is easily enraged and throws tantrums if anything or anyone doesn't act the way he wants them to. Regulus also forces women he finds to his liking to become his wife, and has dozens at any time.
He has two powers as the Bishop of Greed, which compliments each other: "Time stop" and "the Small King".
He can stop time of his own body or anything he touches, making it invincible. However using time stop also stops his own heart, so this ability is unusable by itself. "The small King" allows him to superimpose his own heart on someone else's, allowing him to have a beating heart even while his own is stopped. You'd have to kill that other person, or remove Regulus' heart from him/her first to inflict any damage.
"Time stop" was also his primary method of attack - he would use his foot like a shovel and kick dirt or mud or whatever at people, and due to the object's time being stopped, it would become basically an unblockable attack and would cut through things like butter.
When Subaru and co. fought against Greed, Emilia first removed the fake hearts from his wives' bodies by putting their bodies in cryostasis with ice magic. After the heart moved to Emilia. Subaru's "invisible hand" ability becomes useful for the first time as it's used to remove the fake heart from her body.
Regulus was killed by Subaru and Reinhart in act 5, and had his Bishop ability absorbed.
Sirius Romanée-Conti, Bishop of Wrath - Self-claimed wife of Betelgeuse. Like her husband, she is completely insane.
She controls flames and fights using chains wrapped around her.
Her fighting ability is very strong, enough to fight against Reinhart for a short while.
Her ability as Bishop of Wrath is to impose her own emotions to others in a large radius, turning them into her puppets.
Even worse, any damage she receives becomes imposed on everyone she controls, thus hurting her results in mass death of civilians around her.
Capella Emerada Rugunika, Bishop of Lust - Possibly the biggest piece of shit in the cult.
Most bishops while insane, follow some type of belief. But Capella seems to be sane, just completely vile and evil.
She wants the whole world to love her and only her. She enjoys shitting on people's pride and values by toying with them.
Her power as a Bishop is shapeshifting, both herself and others. Capella turned all her hostages into giant flies.
She either takes a form that's attractive to her victim, or a form that's powerful such as a Black Dragon.
Capella's true form is unknown, but she seems to be at least part dragon.
Her dark dragon blood invaded Subaru's body, causing his body parts to turn pitch black.
They are apparently toxic to most, as Cruche suffered massive pain by being inflicted by it.