The Crimson Binome
Hero
Sure, my group of four players (wizard, paladin, barbarian, warlock) took on the Tarrasque when they hit level 20. It was their seventh encounter of the day, too.5th edition, specifically, but I'm also curious about how encounters went in other editions.
It went about as you might expect. They tried to stay at range, but found themselves ineffective at doing so. In melee, the barbarian and paladin were swallowed within a few rounds, while the wizard did the heavy lifting with his Titan power armor (although the Tarrasque did manage to destroy that before the end of fight, and the wizard was rather put out considering that he burned his ability to Wish in order to acquire that). The warlock played it safe by hiding in a Force Cage and spamming lesser cantrips (Chill Touch, maybe?), since Eldritch Blast didn't work; although the Tarrasque wandered out of range near the end of the fight, when there were no other targets visible and it realized it couldn't crack the cage. It would have been a TPK, if the Tarrasque's stomach wasn't such a friendly environment from which to attack, and the fighter-types eventually finished it off from the inside.