'Tis a good season for children, a better one for toy makers. Here]s what's apt to be in short supply.

The most uttered words in Santa's ear in days ahead could be "Transformers," "Cabbage Patch" and "Masters of the Universe." His chuckles might as easily come from mirthful toy manufacturers, who stand to gross 13.4 billion dollars in 1985--a respectable 12 percent jump in sales.

Buyers of toys and games this Christmas should expect hassles. Popular items will be in short supply, because retailers will be afraid of getting stuck with too much on their shelves. Although 1984 was a good year for toy sales, the Christmas season fell short of expectations. "Most retailers spent 1985 getting rid of inventory from lst year," says Tom Murn, editorial director of Toy & Hobby World.

Last year's best sellers are likely to repeat, but a few new entries--such as Teddy Ruxpin bears and Pound Puppies--are selling out quickly. For a look at what's hot this year in the world of toys and games--

Action Figures
Transformers by Hasbro became the No. 1 toy in the U.S. in May and are expected to be at the top of the heap this Christmas. The 100 million dollars in revenue they brought to Hasbro in 1984 should swell to 300 million this year, industry sources say. New models include insects, dinosaurs and a robot that converts into a microscope that magnifies 14 times.

Mattel predicts its 31 Masters of the Universe charactes will bring in 450 million worldwide this year, up 30 percent from 1984. If Masters of the Universe were a corporation, Mattel boasts, it would rank in the Fortune 500.

Growing in popularity is Matchbox's space creature Voltron, based on a Saturday-morning TV program. Priced from $18 to $70, some larger Voltron versions have removable parts.

Though Voltron and other action figures are predominantly male, manufacturers have come up with a line of female power fighters. After a survey showed that 20 percent of the buyers of action figures were girls, Mattel came out with She-Ra: Princess of Power, and Galoob produced Golden Girl, Guardian of the Gemstone.

Dolls and Stuffed Animals
This is the year of the bear. In addition to Kenner's $16 Care Bears, there are Furskins by Xavier Roberts, which cost $60, A. G. Bear from Axlon for $30 and Teddy Ruxpin made by Worlds of Wonder. Ruxpin is a high-tech, animated bear with an internal cassette that talks. The bear can even tell stories out of illustrated storybooks. The price: $65 to $90.

Coleco's Cabbage Patch Kids, which started a trend, "will turn into a long-lived, high-volume staple," says analyst Paul Valentine of Standard & Poor's. Riding the coattails of Cabbage Patch, Golden Ribbon Playthings of New York has introduced the Huggym Bean black doll for $25. Tonka's Pound Puppies, huggable mutts, are selling for $18. For preschool boys, Hasbro has come out with a large cuddy doll for boys called My Buddy that can withstand rough play.

Demand for such cuddly characters pushed sales of plush dolls from 281 million dollars in 1982 to 544 million in 1984. The upward trend should continue this year and next. Sales of traditional dolls lagged last year, at 1.3 billion dollars, bu Barbie continues to do well. To keep her up to date, Mattel has given Barbie a personal computer, an exercise room and an attache case with a play calculator, credit card, newsmagazines and business cards. For night, she has elegant evening attire.

Old Favorites
They've been around awhile, but many ordinary toys continue to sell steadily. "There's still excitement about basic items," says Douglas Thomson, president of the Toy Manufacturers of America. "In most places I've visited, Lego construction assortments already are sold out, and Play-Doh may be hard to find."

Still showing up in Santa's bag this year are Slinkys, puzzles, Colorforms, Brio wooden-train sets, dollhouses, electric trains, Crayolas and cowboy outfits and guns. A new construction toy introduced by Matchbox is Linkits, made up of plastic connectors.

Games
Thanks to Trivial Pursuit, the big money for the billion-dollar boardgame industry is with the adult audience. While the Selchow & Righter game remains in vogue, its sales in 1985 are expected to be just half of the 20 million games moved in 1984.

Some of the luster has been stolen by more than 80 competitors, including one on trivia about Notre Dame University. Milton-Bradley's Stage II requires players not only to answer trivia questions but to be first to identify a unifying theme for the answers. Sexual and Biblical trivia games are in greatest demand.

Also catchin on among board games is Supremacy, the Game of the Superpowers, a $40 game in which players can move armies, acquire nations and even decide whether to launch a nuclear attack.

A bigger favorite this year: Murder-mystery role-playing games. Among them are How to Host a Murder, Murder to Go, Who Killed Roger Ellington? and Murder at the Mission. Also popular is a video version of the board game Clue.

While demand for games and toys always peaks at Christmas, the industry is trying to spread sales out through the entire year. The share of toys and games sold in the October-to-December quarter dropped from 85 percent in 1979 to 55 percent last year. Some companies will introduce their 1986 products this December, and many are planning big campaigns for Easter toys.

"If there's a problem, it's that a small number of companies--Hasbro, Coleco, Mattel, Tonka, Tomy and Kenner--seem to dominate the industry," says Thomson. "Their success makes it difficult for the small company with similar products."

For 1986, the industry anticipates that electronic games and traditional dolls will continue their decline in popularity but that sales will increase for action figures, bears, cuddly dolls and games.

Rather than come up with bold new products, toy makers are reaping profits from new verions of the same Cabbage Patch dolls, Transformers and Masters of the Universe. Half of today's top 20 toys have been around two or three years.