You’re out there catching ‘em all, but have you ever stopped to think about which one would literally crush the pavement? It's a weird question. Most people guess Groudon because, well, look at him. He’s a massive, prehistoric continent-shaper. But the answer to what pokemon is the heaviest is actually a bizarre tie that proves Game Freak has a very strange sense of humor when it comes to physics.
The Massive Metal Bamboo and the Tiny Space Pebble
So, here's the deal. There isn't just one "heaviest" Pokemon. It's a two-way tie between two creatures that couldn't look more different if they tried. We are talking about Celesteela and Cosmoem.
Both of these weigh in at exactly 999.9 kg (which is about 2,204.4 lbs).
Honestly, Celesteela makes sense. It’s an Ultra Beast that looks like a giant, metallic bamboo rocket ship. It’s thirty feet tall. If you saw that thing coming at you, you'd expect it to weigh a literal ton. But Cosmoem? That’s where things get really trippy. Cosmoem is only four inches tall. It’s tiny. You could hold it in your hand—well, except for the fact that it weighs as much as a small car.
Why is Cosmoem so heavy?
It’s basically a protostar. In real-world science, stars are incredibly dense. A teaspoon of a neutron star would weigh billions of tons. Pokemon doesn't go quite that far because they still need the protagonist to be able to carry it in a backpack, but the 999.9 kg limit is clearly a nod to that density. It's the maximum value the game's code was originally designed to display for weight.
The "Secret" Heavyweight: Copperajah’s Math
If we are being total nerds about this—and we are—there is actually a Pokemon that can technically get heavier than the official 999.9 kg cap.
💡 You might also like: The Combat Hatchet Helldivers 2 Dilemma: Is It Actually Better Than the G-50?
Enter Copperajah.
On its own, this big metal elephant weighs 650 kg. Heavy, sure, but not record-breaking. However, some Copperajah have a Hidden Ability called Heavy Metal. This ability literally doubles the Pokemon's weight in battle.
- Base Copperajah: 650 kg.
- With Heavy Metal: 1,300 kg (roughly 2,866 lbs).
If you’re counting in-battle stats, Copperajah is the undisputed king. It blows past Celesteela and Cosmoem without breaking a sweat. But since the Pokedex only lists "base" weights, it usually gets snubbed in the official rankings.
The Runners-Up: Who Else is Tipping the Scales?
Just because they aren't #1 doesn't mean these heavy hitters aren't terrifyingly large. For years, Primal Groudon was the one to beat. Before the Sun and Moon era introduced the Ultra Beasts, Groudon held the title at 950 kg. It’s still a monster, but it’s officially been relegated to the bronze medal.
Then you have Eternatus. This thing is over 65 feet long, making it the tallest/longest Pokemon in existence. Yet, despite its cosmic horror vibes and massive frame, it only weighs 950 kg—tying with Primal Groudon. It seems like at a certain point, the Pokemon world just stops adding weight.
📖 Related: What Can You Get From Fishing Minecraft: Why It Is More Than Just Cod
The Heavyweight Leaderboard (Official Pokedex Weight)
- Celesteela: 999.9 kg
- Cosmoem: 999.9 kg
- Primal Groudon: 950.0 kg
- Eternatus: 950.0 kg
- Mega Metagross: 942.9 kg
- Groudon (Base): 950.0 kg (Wait, did you catch that? Base Groudon and Primal Groudon actually weigh the same in the games, which feels like a missed opportunity for a "heavier" form).
Why Does Weight Even Matter in Pokemon?
You might think this is just flavor text for the Pokedex, but weight actually changes how the game is played. There are specific moves that rely entirely on how much the combatants weigh.
If you’re using Grass Knot or Low Kick, you’re going to do massive damage to Celesteela. These moves calculate damage based on the target’s weight. Since Celesteela is at the cap, it takes the maximum possible base power from these attacks.
On the flip side, moves like Heavy Slam and Heat Crash look at the user's weight compared to the target. This is why Copperajah is so dangerous. When it has the Heavy Metal ability and uses Heavy Slam, it’s hitting with a power that almost nothing in the game can withstand. It’s like being hit by a falling skyscraper.
The Logistics of a 2,000-Pound "Nebby"
We have to talk about the anime for a second. In Pokemon the Series: Sun & Moon, Lillie carries Cosmoem (nicknamed Nebby) in her bag. She’s just a regular kid. If Cosmoem weighs 2,204 lbs, Lillie is secretly the strongest human in the multiverse. She's casually strolling around with the weight of a Toyota Corolla in her backpack.
The games try to hand-wave this by saying Cosmoem "floats," but physics doesn't work that way. Even if it’s floating, that mass still exists. If she tried to turn a corner too fast, the momentum would send her flying into the next town.
👉 See also: Free games free online: Why we're still obsessed with browser gaming in 2026
How to Use This Knowledge in Your Game
If you're looking to build a team around these heavyweights, you should focus on moves that exploit that mass. For a Celesteela build, Heavy Slam is a must. Because it’s so heavy, it will almost always hit for the maximum 120 base power against most opponents.
Also, keep an eye on Mudsdale. It didn't make the top of the list, but at 920 kg, it's the heaviest "normal" Pokemon that isn't a Legendary or an Ultra Beast. Its Stamina ability makes it even tankier every time it gets hit.
To truly master the heavy-hitter meta, you should hunt for a Cufant with its Hidden Ability. Evolve it into a Copperajah and make sure it has Heavy Metal. Pair it with a Choice Band, and your Heavy Slam will quite literally flatten almost anything that doesn't resist Steel.
Check your boxes for a Celesteela or a Cosmoem and look at that weight stat. It's a reminder that in the world of Pokemon, size really doesn't always correlate with how much you'll break the scale. Just don't ask Lillie for lifting tips unless you're prepared to hit the gym for a few decades.