TCG Land
To stop the combo from going BRR.
Nibiru, the Primal Being
This card is abused many times in combos involving 2 specific machine-type link monsters.
Deskbot 001
This card has an attack cost of sending 2 cards you control.
Super Express Bullet Train
Duelist Genesis
Stardust Dragon
Kaijus
Kaiju
Monkey flip.
Subterror.
Once banned, this card coined the term for many boss monsters that came after it.
Apoqliphort Towers
An old-staple XYZ that could protect itself twice and no one dared to try to out it.
Wind-Up Zenmaines
Breakers of Shadow
Enlightenment Paladin
Divine Comedy
Burning Abyss
Despite seeing zero play in the TCG meta, a certain card from this archetype dominated the Duel Links meta for its Dark Law like effect.
F.A.
This synchro monster has been prominent in many FTKs featuring cards such as Cyber-Stein.
Power Tool Dragon
A fragment of its pre-errata self, any monster this card destroys by battle is banished instead. Still recycles a card though.
Dark Magician of Chaos
Dark Neostorm
Firewall eXceed Dragon
Ultraman
Neos
Noble Knight
A small archetype of 5Ds, these monsters must trigger their EP effect despite the fact that you can't even fully resolve the effect, nor have appropriate targets.
The wiki has a long list of rulings about these cards...
Majestics
Majestic Star Dragon
Majestic Red Dragon
Secrets of Eternity
Rune-Eyes Pendulum Dragon
Kamen Rider
Masked HEROs
Inzektor
Pot of Greed, now this is pod racing.
Cardcar D
This card is like a reverse Chaos Ruler, looking for key cards such as Solemn Warning and Soul Charge.
Kuribandit
Gladiator's Assault
Elemental Hero Chaos Neos
Akira
Metalfoes