Thunder Dragon + Aqua Snake → Kairyu-shin

Thunder Dragon + Spike Seadra → Twin-headed Thunder Dragon

Thunder Dragon + 30,000-Year White Turtle → Kairyu-shin

Thunder Dragon + Kappa Avenger → Kairyu-shin

Thunder Dragon + Kanikabuto → Kairyu-shin

Thunder Dragon + Zarigun → Kairyu-shin

Thunder Dragon + Destroyer Golem → Stone D.

Thunder Dragon + Barrel Rock → Stone D.

Thunder Dragon + Minomushi Warrior → Stone D.

Thunder Dragon + Stone Ghost → Stone D.

Thunder Dragon + Kaminari Attack → Twin-headed Thunder Dragon

Thunder Dragon + Tripwire Beast → Twin-headed Thunder Dragon