-- Publishers Weekly , 2/15/2010 Picture Books Shark vs. Train by Chris Barton, illus. by Tom Lichtenheld. Little, Brown, $16.99 (40p) ISBN 978-0-316-00762-7 This is a genius concept—the kids' equivalent of a classic guy bull session, centering on two playmates' favorite toys. So, who's better—Shark or Train? That all depends. When trick-or-treating, Shark is the clear winner, thanks to his intimidating smile (“The clown is very hungry,” he says, as a bowl of candy is poured into his bag). But in a marshmallow-roasting contest, Train triumphs by virtue of his built-in, coal-stoked rotisserie. Just when readers will think the scenarios can't get more absurd (bowling, a burping contest), the book moves into even funnier territory: hypotheticals in which neither comes out on top (their imposing presences make them ripe targets for getting shushed in a library, and their lack of opposable thumbs means neither is very good at video games). Lichtenheld's ( Duck! Ra