"Thunder Dragon" is an archetype of LIGHT and DARK Thunder monsters. Though members have existed since the Vol.7 Booster Pack in 2000, they only gained the status of archetype with the new "Thunder Dragon" cards featured in Soul Fusion booster pack, in 2018.
The general design and effect of each "Thunder Dragon" monster is based on and inspired by the original "Thunder Dragon", all of them being electrified dragons with a green, yellow, black or gray color scheme. "Thunder Dragon Titan" is especially influenced by the original "Thunder Dragon", which looks like a three-headed version of that monster, similar to the design of "Blue-Eyes Ultimate Dragon". "Thunder Dragondark" is a directly retrained version of the original "Thunder Dragon" as it has the same Type, Level, ATK, DEF, opposite Attribute, and similar effect of searching another copy of itself.
The archetype aims to provide card advantage and thin the Deck with various discarding and banishing effects. Almost all the "Thunder Dragon" monsters can discard themseves to activate a particular effect, generally revolving around searching another copy of itself or retrieving "Thunder Dragon" monsters in the Graveyard or that are banished, and a second effect that triggers when they are banished or sent from the Field to the Graveyard. In addition to this resource-providing mechanic, the Main Deck also contains a more straightforward, aggressive option, "Thunder Dragonduo", that can be Special Summoned by banishing 1 LIGHT and 1 DARK monster from the Graveyard, which can be used to trigger the effects of "Thunder Dragon" monsters. Also, after destroying a monster by battle, it can search any Thunder monster, which can give access to otherwise hard-to-search monsters, such as "Thunder King Rai-Oh" and "Denko Sekka".
The main bosses of the theme are the Fusions "Thunder Dragon Colossus" and "Thunder Dragon Titan". They have respectable stats and both of them can be Fusion Summoned with the traditional means — and the archetype in fact has a Fusion Spell Card, "Thunder Dragon Fusion", that recycles Thunder monsters as materials —, but also have an alternative Summoning condition that exempt the use of a Fusion Card or Effect. Their effects put more pressure on the opponent, by either serving as a one-sided "Mistake", or by destroying their cards on the field when a Thunder monster activates its effect in the hand. Their toughness also stems from their mere presence on the field, as they can banish cards from the Graveyard to prevent their destruction, which can be used to trigger the second effect of a "Thunder Dragon" monster(s).
Generic Thunder monsters that may help the Deck — and that can be searched by "Thunder Dragonduo" and "Fusion" — include "Batteryman Solar", "Thunder King, the Lightningstrike Kaiju" and "Thunderclap Skywolf": the former can send a "Thunder Dragon" monster to the Graveyard, for it to be retrieved, banished or Special Summoned. It can also be used with its Token as Link Material for "Some Summer Summoner" or "Thunder Dragon Goliath". The latter can be sent from the Deck to the Graveyard with "Solar" in order to be Special Summoned by "Some Summer Summoner", disrupting the opponent's plays by destroying their face-up monsters (it can also be discarded and Summoned by "Summoner").
Due to the Deck being composed of LIGHT and DARK monsters that benefit from being banished, popular cards like "Gold Sarcophagus", "Chaos Dragon Levianeer", "Black Luster Soldier - Envoy of the Beginning", and "Allure of Darkness" can be helpful tech choices.
Despite the Deck's sheer versatility, it still has many great weaknesses. Since the deck is so reliant on banishing cards, a well timed "Imperial Iron Wall" or "Chaos Hunter" can completely shut the Deck down, and because it is also reliant on Special Summoning constantly to achieve swarming and field control, cards like "Vanity's Ruler", "Vanity's Fiend", and "Fossil Dyna Pachycephalo" can severely slow down the strategy.
The inherent protection against of the "Thunder Dragon" Fusion monsters can also be bypassed by cards like "Invoked Raidjin", "Kaiju" monsters, "Castel, the Skyblaster Musketeer", "Book of Moon", "Cyberse Quantum Dragon", etc. Curiously, effects that banish them can also be helpful, since the Fusions themselves cannot be Summoned once they are banished and don't trigger any effect upon being banished.
Finally, all three of the "Drain" Continuous Trap Cards can put a complete seal on these Decks. In addition to the on-field effect negation of "Skill Drain", "Soul Drain" will prevent the triggering of effects of "Thunder Dragon" that hit the Graveyard or that are banished and "Mind Drain" prevents "Thunder Dragons" from activating their effects in the hand.