He only appears in-game after the player reaches Stage 20.
A skilled Duelist who finished second in the Regionals, Rex Raptor's strategy focuses on having his Dinosaurs stomp all over his foes with an aggressive offense. His prized possession is the rare "Red-Eyes B. Dragon," which he spent his lifetime to obtain.
After the player advances to Stage 20, they will encounter Rex for the first time, who will be taunting Josh in the middle of their Duel. Shortly afterwards, Rex defeats Josh with an attack from his "Two-Headed King Rex", before proceeding to tell the player that his "prehistoric pals are not to be messed with," and that his monsters will lead him to the top of the "kingdom."
Until the player defeats Rex for the first time, whenever they challenge Rex to a Duel, he will be mildly surprised and rhetorically ask the player if they want to Duel against his dinosaurs. He goes on to admit that he's impressed by the player's guts in challenging him, but also warns the player that his "prehistoric predators" are "ginormously powerful." Rex then prompts the player to Duel, before declaring, "My Duelin' dinos will tear you to shreds!"
Upon Rex's first defeat, he briefly expresses surprise, before attempting to save face by claiming that he only lost because he went easy on the player, despite admitting he had said that he wouldn't. After an awkward pause, Rex swears that he won't let the player win the next time, saying that his dinos won't go extinct again and that the player can't fossilize them forever.
After the player redeems their final unclaimed reward for Rex Raptor's Character Unlock Missions, they will encounter Rex again, who brags that he finished second place in the Regionals with his skills - specifically, skills that he'll now use to defeat the player. He then warns the player that if they think of him as a one-trick pony with his dinosaurs, they're making a big mistake, as Rex immediately reveals his "Red-Eyes B. Dragon" card to the player. He chuckles, and claims that he sees the player quaking in their boots. Rex then admits that although "Red-Eyes B. Dragon" isn't a dinosaur, it's as strong as any of them, and that it will stomp the player flat, before he bursts into laughter.
Can be used each time your Life Points decrease by 1800. In the Draw Phase, instead of doing a normal draw, draw a random level 5 or more monster
Can be used if a Level 6 Dinosaur-Type monster is on your field. If that monster attacks a monster in a Defense Position this turn, the opponent takes battle damage equal to the amount that ATK exceeds DEF. This skill can only be used once per turn.
Whichever player has double or more LP than the other takes double battle damage.
Dinos Find a Way
Can be used each time your Life Points decrease by 1800. In the Draw Phase, instead of doing a normal draw, draw a random Dinosaur-Type monster.
Can be used each time your Life Points decrease by 1800, and you have a Dinosaur-Type normal monster on your field. That monster can attack twice during the Battle Phase, this turn. This skill can only be used once per turn.
Most of the time when he declares an attack with that monster, he announces "I attack with Crawling Dragon #2!"
Whenever Rex Summons "Megazowler", a cut-in frame of Rex's face will briefly appear, and he'll announce "This'll kick your butt back to the Stone Age!" followed by "Go, Megazowler!"
Most of the time when he declares an attack with that monster, he announces "Megazowler, Horn Ramming Charge!"
Whenever Rex Raptor Summons "Red-Eyes B. Dragon", a cut-in frame of Rex will briefly appear, and he'll announce "You've never seen a rare card like this before!" followed by "Red-Eyes Black Dragon!" If that player hasn't already Summoned "Red-Eyes B. Dragon" during that Duel, a cutscene of "Red-Eyes B. Dragon" being Summoned will play afterwards.
Most of the time when he declares an attack with that monster, he announces "I attack with Red-Eyes Black Dragon!" followed by "Inferno Fire Blast!"
Whenever Rex Summons "Sword Arm of Dragon", a cut-in frame of Rex's face will briefly appear, and he'll announce "See how ya like this card! Sword Arm of Dragon!"
Most of the time when he declares an attack with that monster, he announces "Go, Sword Arm of Dragon!" followed by "Sword Tail Slash!"