Child's Play is the 14th episode of Dinosaur King, in Series 1.
In Italy, a Pachycephalosaurus card activates. Oddly, the dinosaur's thick head dome is shining brightly with its own light, and it uses it to straighten the Leaning Tower of Pisa!
Meanwhile, the D-Team is waiting in line for a limited-time-only-offered pudding, until Max sees the news showing a Pachycephalosaurus in Italy, and heading for Rome. At Zeta Point, Dr. Z reveals that it is one of his Secret Dinosaurs, that he raised it from an egg, and that he fused a Move Card into its skull dome. He also announces that he will personally accompany the A-Team in catching it.
At the D-Lab, Dr. Taylor and Reese ponder the light on Pachycephalosaurus' head, while the D-Team teleports out. Then, Dr. Taylor slips out to try and get the pudding the D-Team didn't have a chance to get. Also on the move, the Alpha Gang is heading to Rome in a speedboat, but they go too fast, the controls break, and they crash into a whale.
When the D-Team arrives, they spot the dinosaur, and "borrow" three bikes to follow it on. The Alpha Gang find it, but it runs off. Then the D-Team catch up to it again. They send out Ace, but have to recall him when Pachycephalosaurus is too fast and strong. Then it runs after the sun, which has just broken through the clouds.
It soon encounters the Alpha Gang, and Dr. Z tries to have a heartfelt reunion, but the D-Team shows up. Dr. Z tries to make Pachycephalosaurus attack them, but it just turns and smashes a window that was reflecting sunlight. Ed tries to summon Tank to make it follow orders, but Dr. Z hits the card away: no one attacks his dinosaur without his permission! Unfortunately, the card flies off and lands in the Mouth of Truth, a stone face that bites off the hands of liars. Both Ed and Zander stick their hands in at once, and they both get stuck, blaming the other for hiding something.
Dr. Z jumps onto Pachycephalosaurus, hanging on to the spikes on its head, but it tries throwing him off. When he succeeds, Dr. Z becomes convinced that his dinosaur hates him (not too far off), but Pachycephalosaurus chases a plane that glints in the sunlight, so the D-Team and Alpha Gang chase after it.
They soon reach the Roman Colosseum, where Dr. Z tries to use an Alpha Ball on Pachycephalosaurus, but it smashes it and turns on the Alpha Gang. They summon their dinosaurs, and the D-Team summons theirs, and a three-way battle ensues, with Pachycephalosaurus repeatedly jumping between all three sides. Eventually, it is the only fighter left standing, and humbly approaches Dr. Z, but when he hugs its head, it throws him into the air. It then runs up the Colosseum, jumps off the edge, and shoots a Laser Ray blast at the clouds blocking the Sun, but runs out of energy, and returns to a card.
Ursula trips up the D-Team with a handful of marbles and catches the card, but Dr. Z falls from the sky and onto her, making her drop the card, and Max catches it. Meanwhile, Zander and Ed managed to free their hands from the Mouth of Truth, only to realize neither has Tank's card, so the stick their hands back in again, and become stuck once again.
Back at the D-Lab, Reese is examining the Pachycephalosaurus card, saying how it is fused with a Move Card. Also, Dr. Taylor managed to get the very last cup of pudding, but it gets spilt on the floor when Max tries to take some, and their dinosaurs lick it all up.
Rex/Ace vs. PachycephalosaurusEdit
It rams its head into a column, knocking it down and starting a domino effect of collapsing columns heading for Ace! Rex recalls Ace just in time to avoid the falling columns.
Pachycephalosaurus wins (technically)
Alpha Gang vs. D-Team vs. PachycephalosaurusEdit
After the Alpha Ball is destroyed, Pachycephalosaurus turns on the Alpha Gang, so Ursula summons Spiny and Dr. Z summons Terry, who attack. In an attempt to even the playing field, the D-Team summons Chomp, Ace, and Paris. Chomp and Ace rush into battle, fighting back the Alpha Gang while Pachycephalosaurus runs off after the Sun.
Spiny follows Pachycephalosaurus. Chomp tries to follow, but is hit away by Terry, who uses Neck Crusher on him, throwing him at the wall, but Paris jumps between it and Chomp, taking most of the impact, and collapses defeated.
Ace jumps between Pachycephalosaurus and Spiny, but Pachycephalosaurus jumps on him then jumps off, distracting him, and letting him take the full force of Spiny's Tail Smash attack, which defeats him. But when clouds block the Sun, Pachycephalosaurus charges Spiny, striking him with its head and defeating him in only 5 hits!
It then runs down, stopping Terry from attacking Chomp, then jumping on Chomp's back and striking him with its head. Terry knocks Chomp away as Pachycephalosaurus jumps off, but its head starts glowing brighter than ever as it prepares for a Secret Move attack. Then Dr. Z and Max turn to attack it together. Dr. Z activates Neck Crusher as Chomp uses Lightning Strike, but Pachycephalosaurus ducks under the attack and blasts both Chomp and Terry with a powerful Laser Ray.
Terry is defeated, and Chomp is immobile with exhaustion, and out of the battle for all intents and purposes.
Pachycephalosaurus wins (essentially)
(the Alpha Gang are watching Pachycephalosaurus on the news)
-Dr. Z: "This is amazing. It's the moment I've been waiting for!"
-Ursula: "I don't see what the big deal is: so you finally got cable TV."
-Ed: "Do you think we'll get the Cooking Channel?"
-Dr. Z: "I'm talking about the dinosaur, you dimwits."
(Pachycephalosaurus is charging up energy for an attack)
-Ursula: "Dr. Z, what's that light mean?"
-Dr. Z: "It's a Super Move!...Or something else..."
-Ursula: "You have no idea, do you?"
(after its attack)
-Dr. Z: "Oh, that's right! I could use Laser Ray attack!"
-Ursula: "Aren't you the one who created him?"
- This is episode is the first to debut a Secret Dinosaur and to already give it a name. This episode is also the very first show a wild dinosaur as a chibi besides the D-Team's and Alpha-Gang's. Later secret dinosaurs to appear have nicknames as well.
- At the end when Dr. Taylor yells, "Paris, save me some of that!", it is actually Ace who is eating the spilled pudding, though Paris and Chomp are standing next to the cup as well.