What was the book where a lizard climbed into a brain machine with a boy to save the planet? I think it was a lizard - definitely some pet - and it gave them extra brain power to save everybody. I read this book (maybe short story) back in high school (~1998) & I haven't been able to get it out of my mind or find any information about it.
This is most likely Alan Dean Foster's The Tar-Aiym Krang (1972), the story of a psychic orphan named Flinx (short for Philip Lynx) and his flying, poison-spitting minidrag Pip, who are recruited by Commonwealth agents into an interstellar quest for an ancient alien device.
Flinx, the agents, and the merchant captain they've hired follow the clues to a building on a desolate planet filled with alien ruins. While Flinx, the agents, and the merchant captain explore the building, a ship carrying the unscrupulous Rashaleila Nuaman arrives in orbit to steal the discovery to sell it to the rival Aann Empire.
In the building, the team finds a raised dais with a transparent domelike helmet mounted overhead, but the team begins to leave as Nuaman sends a team of warriors to take over the discovery. Pip flies away from Flinx and settles under the helmet, and the planet's surface begins to shake. Flinx runs to retrieve the minidrag, but as soon as his head passes under the dome he falls unconscious and the dome bursts into color. The ancient alien device powers up, releases Flinx's blocked psychic potential, and destroys Nuaman's shuttle and ship.
Flinx's powers are then put to use in 12 additional novels.