Quote from Kingdragin >>

It's better in some aspects and....worse in others

Art > Amazing, terrifying, to scale, fantasy godzilla (not goofy dinosaur)
Stats > Nothing to say
Resistances > I hate you, this invalidate martials so much and there's no bypassing it (sort of)
Attacks > Less attacks but nasty statuses, thunderous below is cool but lacks range and damage.
Glaring flaws > Where's regeneration ? Where's the effects that prevent you from just flying 500ft above it and peppering it with arrows ? Being a Prone condition machine is NOT good fun at the game table, it's infuriating and more a bad encounter design. Also the attack bonuses are still insane and trivialise AC since it will always have a base minimum of 21 to hit (by rolling a 2) which is PLATE +3 (a legendary item) meet to beat ! And because it's a Prone machine (some without saves btw) it will pretty much always have advantage on it's targets.
Initiative > What were you smoking with these monsters ? Why does the tarrasque has expertise in Initiative ?

If you're going to make comments like this at least do it in a good faith way and don't be selective with your figures.  Basic plate, a shield and cloak of protection give you an AC of 21 with just an uncommon item.

I was referring to a more traditional attack and highlighted that. The wording I used could have been more precise, admittedly. 

I was gaming this out a bit, and level 20 Monks are actually kind of insane vs a Tarrasque. Resistance to everything except Force which isn't a problem here. Bite attack they deflect and take no damage. They resist against 2 claw attacks and take 28 average damage that round. Eating a Monk would actually be the worst thing the Tarrasque could do, as they'd resist the Acid damage down to 28 and then likely completely deflect the remaining damage while being otherwise safe.

Being level 20 and fighting a Tarrasque I'd assume +3 unarmed wraps are available, giving the level 20 Monk a +16 to hit. That's a 60% chance to hit assuming they aren't restrained. Assuming 24 Dexterity and the +3 wraps with 5 attacks that's 82.5 Force Damage per round * .6 = 49.5 average DPR against the Tarrasque. That obviously dips once they're eaten, but that dip is fine considering they're also not or at least rarely taking any damage while eaten.

There are obviously a lot of other factors at play, like does the Paladin Shining Smite to further increase DPR? Does the Monk have a Blood Fury Tattoo? Variables will come into play and not everything will work out, but an end game Monk is extremely solid here.

To all those who have concerns regarding the Tarrasque's lethality or lack of regeneration: don't. So far, the discussion has focused on how well the Tarrasque would fare theoretically in the context of "lore" and what a "world destroying monster should be capable of." First and foremost, let's dismiss the issue of regeneration. It's just an abstraction for hit points (for example, if the tarrasque had the troll's regeneration, the issue would then be flaming arrows from 600 feet away). But consider, why shouldn't the Tarrasque be able to be whittled down by enemies (or be forced to retreat underground)? Seems like a perfectly reasonable occurrence. Will it happen? No. For example: the theoretical ranged attacker. If the attacker is within 150 feet (it's more than that since the Tarrasque can move as a legendary action and jump), then the Tarrasque can damage the attacker implicitly. If the attacker is beyond that range, then the attacker will miss most if not all of their attacks. Additionally, as several have alluded, when a group confronts the Tarrasque, the group will certainly not have the luxury of waiting for this strategy to succeed (or, as I explain, fail) because the Tarrasque can wipe out a city and leave before this intrepid ranged attacker(s) could slay it (attacking at disadvantage vs. an AC of 25 and dealing half damage). Moreover, these concerns are baseless because they necessarily ignore the options available to the DM. Consider: what does the ranged attacker do when the Tarrasque scopes up some earth and rocks and hurls it at the attacker? If the DM uses the Improvising Damage table for falling rubble, then the attack must make a Dexterity saving throw to avoid 4d10 damage (voilá). If the DM instead wants to make it an improvised attack, then it's your AC vs. d20 + 10 (at disadvantage) with the Tarrasque dealing 4d4 + 10 damage. What if there's a thunderstorm, and the ranged attacker has to content with bolts of lightning (Dex save vs. 2d10, per DMG) or other creatures? I'm not trying to be dismissive, but these theoretical discussions are so dull. Everyone knows these scenarios have no real bearing on what actual challenges a group will face. If you want a truly indestructible monster, they literally gave it to you: "Its threat can never be wiped from the multiverse."

This is..stupid. It's better then the 2014 version, but they chose the laziest option possible in the form of the breath weapon to try & fix the problem. At least it has the ability to burrow back & is a little faster, but it still should have regeneration. And I'd upgrade the burrowing to straight up earth glide, which it also used to have, and frankly I'd nerf the cone attack because again, that just makes it feel like a wingless dragon to me. I don't want to run a tarrasque like that where the big damage is focused into a rechargeable breath weapon. If it needs to have that for range options, fine. I'd leave the prone & deafened effects, but I'd slice the damage in half, so attacking in melee is still the most effective option, if it has targets within reach. Because pummeling you & biting you should be its main way of hurting the party, not an energy cone. Just run a great Wyrm if you want that.

It can also burrow, so a flying archer can't do anything to it once it decides to go land-shark on everyone.

Improvised weapons, just hurl a boulder if you need to

That flying archer better have a way to get more than 60 ft in the air in one round (or be large), otherwise Tarrasque can just make it prone

The spam of psychic lance will be totally worth it. A group of 4 wizards will only need to survive one round...

People are like, “Oh, it’s so easy to kill the Tarrasque! You just need somebody who can fly! And reliably hit an AC of 25! And have unlimited ammo! All while it’s destroying that city down there! Well, it took me like an hour, and the city is just rubble at this point, but at least I’ve worked it down to almost no HP. Whoops, it’s burrowing away! Oh, well - we’ll get it next time!”

bro, if I were to use my custom attack, I could kill it in 2 turns

You could kill it with a level 13 copper dragonborn wizard, a Acid Splash cast while flying or dragonborn fly trait, and a +5 in INT. Oh, that's 10 minutes, 90*10.5=945 acid damage. you also have acid Res against his swallow. I also think that they definitely are going to burrow underground, but then they're gone which is great.

Ironically my wizard would survive longer in his belly than out of it. Absorb element will turn the acid damage to a 25, meanwhile she will spam psychic lance from the inside to burn trough its legendary res. It would take 7 to 8 turns to bring her down, more than enough time for her to force that thing to use all its legendary res... And once that down, its stunned locked.

to all the people bemoaning that they have no range attack, then give it this 

Spit. Ranged attack roll +9 hit: the target takes 21(2d10+10) Bludgeoning damage and 35 (10d6) acid damage. miss: the target has the stunned condition until the end of their next turn, as the target spits and gags because of the massive blob of terrasque spit that just hit them

I hope that this is good for you guys

Also he can high jump and tail attack to 150 feet. good bye archer

The habitat being "Urban" doesn't make a lot of sense to me. I thought that it lived underground, not in developed areas.

Quote from wellin_goodon >>

The habitat being "Urban" doesn't make a lot of sense to me. I thought that it lived underground, not in developed areas.

 They gave it that because the thing that it does most of the time is destroy cities and kingdoms

big daddy

Animals evolved to have spikes to prevent bigger things from just chomping down on their back and killing them.

Tarrasques have spikes.

So who's gonna chomp down on his back? (concerned rn)