When TSR released the AD&D Monster Manual II, the Tarrasque was unleashed. The Monster Manual II was a collection of monsters, either written or compiled by Gary Gygax, as was the original. The Tarrasque was a monster to end all monsters, something to let even the highest-level characters break into a cold sweat.
The problem with the Tarrasque in DCC is that it has already been done.
Bear with me. I ask you to consider Mr. Goodman’s The Emerald Enchanter, Mr. Stroh’s Colossus, Arise!, and REDACTED’s NOT OUT YET. Each of these adventures contains an encounter that is a spiritual successor to the Tarrasque.
From Mr. Goodman, we learn that it is allowable to create DCC monsters that the PCs don’t even have a chance to affect. And it is okay to just say a monster does XdY damage to a PC – no attack roll or save required. From Mr. Stroh we learn that sometimes a monster is going to get free environment-altering effects in addition to its attacks. (The Thing in the Chimney used the same for the Cinder Claws, albeit to a lesser extent, when it appeared in time for Christmas 2012. There is nothing new under the sun.) In REDACTED by REDACTED we see that REDACTED REDACTED REDACTED, which is close enough to the idea of the Tarrasque that I hesitate to throw my hat into this particular ring.
So, keep playing through the upcoming DCC adventures. When NOT OUT YET has been out long enough to give people a chance to play it through, I may revisit this topic. And, no, I am not going to reveal the identity of REDACTED at this time. I don’t wish to spoil any surprises. I will just say that I am not the author.