They have powers, they evolve into other characters and they fight duels.
Pokemon, and the 150 other cartoon creatures that make up this legion of forces, have captured the hearts and minds of children throughout the world.
But Pokemon cards have also spawned a disruptive schoolyard craze in Kingman, and several youths now have police records after trying to steal Pokemon games and cards.
Despite the arrival of a new set of Digimon characters, who are not quite as lovable looking, the Pokemon craze shows little sign of slowing down.
"I used to have people coming in every day, calling, calling, calling to ask if we had Pokemon cards.
It's slowing down a little but it is still going strong," said Kellie Kreidel, the customer service manager at Hastings Book Store.
In fact ,Kreidel said she just bought some Pokemon game cards for her own boys.
"Between me and my sister we have five boys between the ages of 5 and 12 and we are still buying game cards," she said.
Because some monsters are rarer than others, children are always on the lookout for the more coveted cards.
"You never know what monsters you are going to get when you purchase the cards," said Tracy Clouse, whose children collect the cards.
She said her son Michael, 12, has collected about 150 Pokemon cards and other paraphernalia, including videos, books, games and lunch boxes for about a year and a half.
But Clouse and her husband, Steve, have put a limit on the spending.
"The cards are somewhat expensive.
Anywhere from $10 to $20 for the starting pack.
He (Michael) has to earn the money for the cards he buys," Clouse said.
Michael once paid $10 for just one card.
"It was worth it.
It was hard to find and rare," he said.
He has collected a few Digimon cards but said he doesn't like Digimon as well as Pokemon.
Betsy Parker, the Kingman Elementary School District acting superintendent said trading Pokemon cards at school became very disruptive and she knows of at least one elementary school within the school district that banned the cards from the school premises.
Introduced in the United States in 1998 via Asia, where these "pocket monsters" were equally as popular, Pokemon has captured the imagination of children from four to 14.
It has also spawned a multi-million dollar Pokemon industry, including everything from Pokemon games, trading cards, stuffed animals and lunch boxes to drinking glasses.
But the big thing with most youngsters is the acquisition of Pokemon cards.
To Yvonne Cossio Pokemon characters that have been around for years, and the new group of Digimon characters, look the same.
"They all look the same to me.
But my children know the difference," Cossio said.
Cossio, a recreation coordinator at the Kingman Parks and Recreation Department, said she buys her children Pokemon T-shirts and gets them the characters at fast food restaurants, but can't afford to get them the cards.
"I wanted to buy them a few packs at Christmas time, but they were all sold out," she said.
It was Pokemon Day at the Summer Fun Club, sponsored by Parks and Recreation, Friday.
The children were allowed to wear Pokemon T-shirts and bring Pokemon books and games, but not the trading cards, Cossio said.
"Kids tend to try to take them.
I think that's why they were banned from some Kingman schools," she said.
Some Kingman youth recently broke the law in an effort to acquire the coveted cards.
On June 3 three youths - ages 8,10 and 12 - stole a Pokemon video game and controller from a vehicle.
Last weekend two 12-year-olds were arrested after they broke a rear door and attempted to enter a home in at attempt to steal Pokemon cards, said Kingman Police Department spokeswoman Tracie McKnight.
"It is sad for kids to have that on their record already," McKnight said.
"It is just a fad," said Clouse of Pokemon, "but who knows how long it will last."