OK the top ten heaviest Pokemon are:
1. Celesteela (2204.4 lbs)
2. Cosmoem (2204.4 lbs)
3. Primal Groudon (2204.0 lbs)
4. Eternatus (2094.4 lbs)
5. Groudon (2094.4 lbs)
6. Mega Metagross (2078.7 lbs)
7. Mudsdale (2028.3 lbs)
8. Guzzlord (1957.7 lbs)
9. Origin Forme Dialga (1871.0 lbs)
10. Stakataka (1807.8 lbs)
Yes, Steel types are on average the heaviest Pokemon, but Ground Types are about the same as Rock types. 16 Ground Type Heavy Weights+Super Heavy Weights and 18 Heavy Weight Rock Types they are about the same as there are no Super Heavy Weight Rock Types.
Fun-facts: The Lightest Pokemon is Ghastly(0.2lb), and the Lightest Steel Type is Jirachi(2.4lb).
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