Hazards, the Grass typing, and options like Knock Off help distinguish Ferrothorn a lot.Thanks! But i do have one question. Ferrothorn also doesnt have reliable recovery, and is siliar to celesteela. While Ferrothorn can setup hazards, cant celesteela be harder to break more and more after leech seed stalling mons? Or does it not get a boost from that/it still doesnt helped?
Also why was it so good last generation as it still had to deal with a stronger Koko, z move nukes, a more popular magnezone, and hidden power coverage?
Celesteela clashes with a lot of team compositions due to it being a Flying type without Defog, causing awkward overlaps or potential vulnerabilities, and it does not have the other practical elements that Ferrothorn has. It is a Pokemon with solid potential, but when it runs into Zapdos, Toxapex, Slowbro, etc. that can hard-wall it and eventually cripple it or pivot around it so often and it has no way of making incrimental progress like Ferrothorn does, it becomes a major liability.
Last generation, Celesteela took a large dip in popularity during the last months of the metagame, but it saw a peak largely due to things like Mega Latios, Mega Alakazam, Mega Pinsir and Z-move Kartana -- none of these these are usable in the current metagame. Overall, this landscape is much less friendly to Celesteela.