Nine-year-old David Greenspan plops down on the floor of his bedroom in Annandale and pulls out his most prized possessions: 122 glossy trading cards packed in a small, clear box. The cards feature exotic-looking creatures, some with wings, some with talons and some resembling big-eyed lizards.

With the ease born of constant repetition, he flips through the pile, rattling off the name of each. Here is Dragonair, he says, and Charmander and Blastoise. Here are Raticate and Pikachu.

David holds out his favorite: a fire-snorting dragon with green wings. It's a holographic Charizard, he says excitedly. "He has 120 hit points, and he can do 100 damage."

If all this sounds faintly familiar yet utterly indecipherable, then you are the parent of a child caught up in the latest toy craze: Pokemon, a Japanese game featuring 151 "pocket monsters" that children do battle with, capture and trade by using the cards or playing one of two Pokemon video games.

Undetected by most adults, Pokemon (pronounced POH-keh-mahn) hit U.S. shores last fall, sweeping over America's preteens with the force of a tsunami.

What's not new about Pokemon is the frenzied pursuit fueling the craze. Remember Strawberry Shortcake and Cabbage Patch dolls? More recent obsessions -- the kind that have parents wandering the Beltway in search of a toy shop without bare shelves -- include Teenage Mutant Ninja Turtles, Mighty Morphin Power Rangers, Pogs, Tickle-Me Elmos, Tamagotchis, Beanie Babies, Furbies -- and, now, Pokemon.

Industry followers note that toy fads are getting bigger and spreading faster than ever. One reason is that manufacturers are more savvy about marketing to children: Why put out just one Power Ranger when you can make five different ones? Also, the Internet and e-mail instantaneously disseminate the word on must-have toys, and baby-boomer parents appear more eager than ever to run out and find them for their children.

"We live in a very competitive society, and nobody wants to feel that their child is going to be left out or, worse, left behind," said New York City educational psychologist Istar Schwager, a consultant on children's educational products. Parents who drive from store to store and wait in line to buy the latest toy may "see this as very tangible evidence that they care about their children," Schwager said.

With Pokemon, all the now-familiar indicators of another toy frenzy are in place: Schools are banning the trading cards and video games (some teachers have even forbidden children to mention Pokemon in class), and frantic parents are in eager quest of the highly sought-after items.

More than 13,000 parents and children showed up for a Pokemon trading card show in Woodbridge, N.J., last month. Stores report selling out within hours, and the $9 price of the 60-card "starter" set has tripled at some outlets. Rarer cards go for as much as $70 each.

"We've never seen anything like this. It's phenomenal," said Ron Savino, co-owner of Collectors World, a Fairfax card and comics store that has had to install an extra phone line to deal with the hundreds of Pokemon calls it gets each week. To restock their inventory, Savino and his partner now bid on cards in Internet auctions.

A lot of little Pokemon addicts are veterans of earlier toy fads.

David Greenspan and his sister, Jamie, 7, share a collection of several dozen Beanie Babies. Jamie, who dismisses Pokemon as "stupid," prefers CrazyBones: She and David have more than 100 of the thumb-size plastic figurines, which recently have skyrocketed in popularity.

Rockville sixth-grader Joshua Dunietz is a virtual archaeological dig for studying toy mania. About the only fad he's skipped in 12 years is Beanie Babies.

His Pokemon collection features 104 trading cards carefully arranged in a thick binder and two videotapes of the Pokemon cartoon show. And he has racked up 250 hours on the Pokemon video game, including the rare feat of capturing all 151 monsters.

Forget basketball. The game Joshua loves is Pokemon.

"It's kind of like collecting, and it's a strategy game," he said. "You actually have to think about where to go and stuff like that. And the names are kind of magical."

The object of the game is to capture and train all 151 Pokemon creatures. Each can absorb a certain number of "hit points" before it is knocked out, and each has certain "damage" power it can use to attack others.

The rules of the game are so intricate that few adults dare wade in, said Cliff Annicelli, associate editor of Playthings magazine. Which could be the point. Pokemon allows youngsters the "feeling of having something all your own that your parents either don't like or don't understand. That has always appealed to young people."

So far, Pokemon has attracted mostly boys, but 7-year-old Dakota Lane said she enjoys playing the game with boys at her Northern Virginia Montessori school while waiting for their car pool. Most of Dakota's female friends just collect the cards because they like looking at the creatures but don't want to play the game, she said. Their favorite is Pikachu, a cuddly-cute creature that resembles an overweight rabbit.

The genius -- or blame, depending on one's point of view -- behind Pokemon lies with Nintendo, the Japanese video game behemoth. After runaway sales in Japan, the company released two Pokemon games for its popular Game Boy in the United States last September. The 2.8 million Pokemon copies sold here make it Nintendo's top-selling hand-held video game.

Spinoffs were inevitable. Nintendo has now licensed 45 other Pokemon products, including the popular trading cards, which were introduced in January; Pokemon lunch boxes; T-shirts; key chains; and posters. The animated television show, which first aired in the United States last fall, is now top-ranked among children's shows in the United States. Coming soon: a line of Pokemon bean-bag toys and a feature-length movie.

Unlike some popular toys with little or no educational value, Pokemon presents a dilemma for some parents who feel that aspects of the game can assist child development.

As with chess, children must memorize each Pokemon's skills and powers and think ahead and strategize in sophisticated ways. Younger children just learning to read can practice that skill, and math also comes into play.

Joshua's mother, Barbara Gesumaria, admits to mixed feelings about Pokemon but says she is trying to look at it objectively.

"It's not a kill-'em-and-shoot-'em game," she said. "So maybe it's a good thing, [maybe] it promotes higher-order thinking. Just because I don't understand it doesn't mean it's a bad thing."

Fairfax mother Marina Hernandez has turned down pleas from her son William, 8, to purchase Pokemon games and cards, although she has bought the T-shirts. Recalling that William saw his Nintendo game repossessed after he became obsessed with it, Hernandez worries that a Pokemon game could hurt his grades. "It disturbs his mind," she said, adding she might reconsider once school is out.

David Walsh, founder of the National Institute on Media and the Family, said that if parents participate in the game, for example, by helping their child collect the cards, it can develop a common interest or shared hobby. But if well-meaning parents simply rush out to purchase all the Pokemon paraphernalia they can find, or allow children to play the game constantly, the advantages evaporate.

"To buy into the `gotta-have-it' doesn't do kids any good," Walsh said. "Instead of teaching them lessons about delayed gratification and patience, we become part of the machine that fuels the instant gratification."

David Greenspan's parents make him spend his own money on Pokemon products, and they rarely make special trips to acquire more. Cindy Greenspan said she and her husband, Jeff, have talked to David about the marketing strategies toy companies use on children. But so far "that doesn't seem to deter him," she said. "We can just hope that eventually the lesson sinks in. We're using it as a teaching opportunity."

She also thinks the game may have an educational component, helping children learn to categorize objects before they are capable of doing it in their heads. "It contributes to math and science skills," she said, "even though the content is ridiculous."

CAPTION: David Greenspan, 9, of Annandale, shows his Pokemon cards. He has 122 of the glossy "pocket monsters" trading cards of the hot Japanese game.