"Maju Garzett" and "Great Maju Garzett" share the DARK Attribute and were both released in Dark Crisis, the former being initially Short Print while the latter was Rare, although they were reprinted as Commons in Dark Revelation Volume 1. Their ATK is based on the original ATK of the monster(s) Tributed to Normal Summon them.
"Gren Maju Da Eiza" was released in the next Booster Pack, Invasion of Chaos, as Common. Its ATK and DEF are based on the number of both player's cards that are banished. It works better as a beatstick in Decks centered around banishing, late in the Duel.
"Legendary Maju Garzett" was released in Secrets of Eternity, it can only be Special Summoned by Tributing all monsters you control, and its ATK becomes equal to the combined original ATK of the Tributed monsters.
"Gren Maju Da Eiza" works in most Decks that banishes cards.
"Legendary Maju Garzett", "Great Maju Garzett" and "Maju Garzett" need easily-Summoned high ATK monsters so they can be used at their full potential. DARK monsters with 0 DEF are the most useful, since they can be recycled using "Recurring Nightmare", which can also return the "Majus" to the hand. "Goblins" and "Giant Orc" suggest "Skill Drain", but it completely cripples the "Majus", so an alternative is "Final Attack Orders", which has the bonus of ensuring Battle Damage against face-down Defense Position monsters. "Forbidden Chalice" won't affect all your monsters like "Skill Drain", can negate the negative effect of your low Level monsters, or give them the extra ATK they might need. "Dark Ruler Ha Des" aids other Fiends by negating the effects of monsters they destroy. Too many high-Level monsters can be dead draws, a problem than can be solved with cards like "The Monarchs Stormforth". "Grave Squirmer", may be useless for the "Majus", but can destroy troublesome cards or be Tributed for another monster, and is an extra target for "Recurring Nightmare"; however, avoid using it with an active "Final Attack Orders". "Battle Mania" forces your opponent to attack an overpowered "Great Maju Garzett", and "Megamorph" can help OTK the opponent. "Vanity's Fiend" ensures your opponent is in the same situation as you. "Dark Necrofear", although collides with the last two, is a staple in Decks with lots of Fiends, and can be Tributed right away to bring a 4400 ATK "Great Maju Garzett". "Ojama Trio" works with "Battle Mania" and/or "Final Attack Orders". Counter Traps or Virus cards can either protect your monsters or give them another use if they are about to be destroyed anyway.