Pokémon players from nearly 30 countries are tweaking their card decks for a world championship tournament in Hawaii this weekend, and they're all hoping to beat a soft-spoken fifth-grader from St. Charles County.

William "Dema" Boatman, 10, is ranked No. 1 in the world among junior players of the trading card game. He's won 82 of 93 matches this year, and along the way, he's racked up two state championships — Missouri and Kansas — a regional championship and $2,500 in college scholarship and prize money. In Hawaii, he'll be competing for a $7,500 scholarship and other prizes.

Dema, whose nickname is short for his middle name of Dmitri, is one of five young people from the St. Louis area invited to the world championship. Two other boys — Dale Conoyer, 10, of St. Peters, and Alex Krekeler, 9, of Maplewood, are in the junior division, too; their world rankings are 50 and 53, respectively. The others, Andrew Krekeler, 14, of Maplewood (ranked 26th worldwide), and A.J. Lester, 15, of Hazelwood (ranked 36th), will compete in the senior division.

"The Demanator," as Dema's competitors call him, hardly looks the part, but he's been practicing the game daily to prepare for the tournament, which will be two full days of one-on-one battles against the 350 best Pokémon players from all over the world.

On a recent night at Yeti Gaming in Crestwood Plaza, Dema's big brown eyes hid the fierce strategizing behind his card play.

"Dema is successful because he is always thinking ahead," said his dad, Chad Boatman. "The game involves not only what you're doing, but understanding what your opponent is doing."

Dema said he got hooked on Pokémon a little over three years ago, when friends talked about playing the game in a league, and he went to watch.

For those who think Pokémon was just a late-'90s fad, the collectible card game still has lots of die-hard fans. The game is based on the Pokémon video game and play centers on "battles." Each player uses a deck of 60 cards that they hand-pick and use to knock out their opponents.

"It's a little bit of chess, a little bit of poker and a little bit of rock, paper scissors," said Boatman, who passes time at the tournaments playing the game with the other "Pokédads" when he's not running his toy and game store, the Neutral Zone at Mid Rivers Mall.

More than a pastime though, Boatman said the game has improved Dema's reading skills, and his younger stepson, Aidan Koenig, understands math better after taking up the game.

"People think it's just a card game, but there are other things he's learning that are important," Boatman said.

Key among those things is sportsmanship, he said. Each Pokémon match begins and ends with a handshake, and players are encouraged to accept winning and losing with grace.

"You have to know how to handle it the right way," Boatman said. "It's that kind of stuff that builds good character."

Dema's success at the game has led to his celebrity status at tournaments, which is not always a positive experience, Boatman said.

"He learned that people really don't like to see him show up, but he knows that's part of the competition," he said.

Dema's success has been a big hit, though, with his classmates at Central Elementary School in the Francis Howell School District, where he's an honor student. His friends were impressed by the medals and trophies he brought to show and tell.

"They were calling him Michael Phelps because he came with his six gold medals, and he let his classmates wear them," Boatman said.

Vince Krekeler, who owns Yeti Gaming and has two sons competing in the Hawaii championship, said Dema is the best young player he's seen in years. His knowledge of the game is so exceptional that Krekeler has asked Dema to act as a judge at several tournaments.

"He knows the rules backwards and forwards, and he does a good job explaining things to the kids," Krekeler said.

Dema is hoping to win this year because he has other interests besides Pokémon. He played soccer at his school, and now wants to try out for a football team.

"I don't know which position it'll be, but I'm going to play," he said.

In the meantime, Dema said he likes the competition of Pokémon, and he's ready to take on the world.