A list (Pokémon that normally have the Levitate ability are bold:
Metapod, Kakuna, Gastly, Haunter, Gengar, Mew, Misdreavus, Mismagius, Unown, Pupitar, Celebi, Silcoon, Cascoon, Slakoth, Vigoroth, Slaking, Plusle, Minun, Vibrava, Flygon, Lunatone, Solrock, Baltoy, Claydol, Castform, Kecleon, Duskull, Dusclops, Dusknoir, Chingling, Chimecho, Latias, Latios, Kyogre, Groudon, Rayquaza, Jirachi, Deoxys, Cherubi, Cherrim, Carnivine, Rotom, Uxie, Mesprit, Azelf, Regigigas, Origin Forme Giratina, Cresselia, Phione, Manaphy, Darkrai, Shaymin, Arceus, Victini, Yamask, Cofagrigus, Archen, Archeops, Zorua, Zoroark, Ferroseed, Ferrothorn, Tynamo, Eelektrik, Eelektross, Cryogonal, Deino, Zweilous, Hydreigon, Cobalion, Terrakion, Virizion, Reshiram, Zekrom, Kyurem, Keldeo, Meloetta, Genesect.
EDIT:
I decided to quickly summarize this
- Most Pokémon that normally have the ability Levitate (Gastly family, Chingling family, Tynamo family, Origin Forme Giratina etc)
- Cocoon Pokémon (Silcoon, Cascoon etc)
- ~Half of the Legendaries
- Pokémon with unique or hindering abilities (Ferroseed family, Regigigas, Archen family, Yamask family, Kecleon, Zorua family, Cherubi family, Plusle, Minun, Slakoth family etc)
EDIT2: Pokémon with the Levitate ability that are in the list are now bold
