They did not always use the Wrecking Crew, but often did, in the studio.
Beach Boys musicianship was poor to average, at best, so they relied on The Wrecking Crew for their recordings.
Tony Asher’s lyrics for PetSounds is HUGELY underrated and made the difference in the critical acclaim.
TWC was a floating group of LA’s best-of-the-best but seem to be centered around drummer, Hal Blaine.
The bass players changed but Carol Kaye played on many TWC tracks.
Other session players included Glen Campbell, Dr John, and so many more.
I have mastering credits for technical assistance on a handful of iconic albums and was gifted a “dry” version of PetSounds...and hundreds of other tracks - dry and studio chatter that never made it to the commercial release.