LilOu
PO poopyhead
The requirements to be in S-Rank are:Why is Keldeo not S-rank? He thrives in Rain and Sand and is probably the best Scarfer available at the moment. Only beaten by Scarf Latios which has a shit ton of downsides.
Keldeo can't sweep alone. He has a decent amount of counters (this pokemons usage has increased because of Keldeo): Latios, Latias, Jellicent, Toxicroak, Tentacruel, Amoongus, Celebi, etc. Just thing about it. These pokemons are hard to take down without the help of a powerful trapper and they are very bulky.Reserved for Pokemon who can sweep or wall significant portions of the metagame with little support.
Keldeo's main set it Choiced. He has not multiple roles that can be performed effectively. If you use Sub + CM you need to get rid of HP ice and hydro pump, so dragonite can be considered as a counter and you have a bad time playing against Lati@s.Also the home of Pokemon who can easily perform multiple roles effectively, increasing their versatility and unpredictability.
I agree that Keldeo is awesome and is the best scarfer, but he doesn't have sufficient capability to become S-Rank.