Hmmmmmmmmmmmmm?
Wairlord is the biggest pokemon at 47 feet, 7 inches.
Groudon is the heaviest at 2094.4lbs or 950.0kg.
The following Pokemon are in the highest band of weight, as described on the Grass Knot page. They take maximum damage (120) from Grass Knot and Low Kick. They are likely to do good damage with Heat Crash and Heavy Slam (depending on the opponent).
#076 Golem #095 Onix #130 Gyarados #131 Lapras #143 Snorlax #149 Dragonite #208 Steelix #226 Mantine #248 Tyranitar #249 Lugia #297 Hariyama #306 Aggron #321 Wailord #323 Camerupt #362 Glalie #375 Metang #376 Metagross #377 Regirock #379 Registeel #382 Kyogre #383 Groudon #384 Rayquaza #389 Torterra #450 Hippowdon #464 Rhyperior #473 Mamoswine #476 Probopass #483 Dialga #484 Palkia #485 Heatran
Biggest: Wailord
Heaviest: Groundon
Hope this helps...
Definitely one of the heaviest pokemon is Groundon. It has whopping weight of 2094 lbs. Another heavy one is Regigigas. It weighs in at 925 lbs. Dialga, Metagross, Snorlax, and Girantina are all weighed over 1000 lbs. The biggest pokemon ever has to be Waillord. At about 47 ft.
Hope this helped :)