EDIT: With this better pic, we can see that the legendary dragons are based on some of the most powerful Dragon-Type monsters in the game:
-Fusion Monster: Hyougokuryuu Trishula (Trishula, the Ice Prison Dragon) (WATER/Level 9)
-Synchro Monster: Shiten Ryuu Judgment (Judgment, the Splendid Celestial Dragon) (LIGHT/Level 8)
-Xyz Monster: Gekimetsu Ryuu Dark Armed (Dark Armed, the Savage Onslaught Dragon)  (DARK/Level 7)
-Pendulum Monster: Shuuen Ryuu Chaos Emperor (Chaos Emperor, the Doomsday Dragon)  (DARK/Level 8)

Wszystkie smoki są. Choc przyznam szczerze- mam spory niedosyt

VJMP-JP148 Kuroganeryuu Darkness Metal (Darkness Metal, the Blacksteel Dragon) Link 4 DARK Dragon Link Effect Monster ATK 2800 Links: Top, Bottom Left, Bottom, Bottom Right Materials: 2+ Effect Monsters with the same Type and Attribute You can only use this card name’s effect once per turn. (1) You can target 1 of your monsters that is banished or in your GY; you cannot Special Summon Link Monsters for the rest of this turn, also Special Summon that monster in Defense Position to your zone this card points to, but that monster’s effects are negated, and if it leaves the field, return it to the bottom of the Deck.

VP18-JP001 Hyougokuryuu Trishula (Trishula, the Ice Prison Dragon) Level 9 WATER Dragon Fusion Effect Monster ATK 2700 DEF 2000 Materials: 3 monsters with different names Must be either Fusion Summoned by using monsters you control or in your hand, or Special Summoned by banishing the above cards you control (in which case you do not use “Polymerization”). (1) If this card is Special Summoned by using only monsters whose original Types are Dragon: You can activate this effect; look at the following in sequence, and banish 1 card from each. • Your Deck. • The top of your opponent’s Deck. • Your opponent’s Extra Deck. You can only use this card name’s effect once per turn.

VP18-JP002 Shitenryuu Judgment (Judgment, the Seraphic Dragon) Level 8 LIGHT Dragon Synchro Effect Monster ATK 3000 DEF 2600 Materials: 1 Tuner + 1+ non-Tuner monsters If you Synchro Summon this card, all the material must be the same Attribute. (1) Once per turn, if this card was Synchro Summoned and you have 4 or more Tuners with different names in your GY: You can pay half your LP; destroy all other cards on the field, also you cannot Special Summon monsters for the rest of this turn, except Dragon monsters. (2) Once per turn, during your End Phase: Banish the top 4 cards of your Deck.

VP18-JP003 Gekimetsuryuu Dark Armed (Dark Armed, the Annihilator Dragon) Rank 7 DARK Dragon Xyz Effect Monster ATK 2800 DEF 1000 Materials: 2+ Level 7 monsters Once per turn, if you have exactly 5 DARK monsters in your GY, you can also Xyz Summon “Dark Armed, the Annihilator Dragon” by using 1 Level 5 or higher DARK Dragon monster you control as material. (1) You can detach 1 Xyz Material from this card, then target 1 card your opponent controls; destroy it, then banish 1 card from your GY, also this card cannot attack for the rest of this turn.