Tell me a Steel type that can actually handle them.
FYI,Water is neutral on Steel. Nattorei is the best for it,but even then,he can't survive against 3 Swift Swimmers.
Use Shedinja?
That's crossing the line already. We're now forced to use a mon that is already super hard to fit onto a team,and adding it just for Rain teams...wtf?
You don't have to worry about SS or Hail killing you,but there's Toxic(From Vaporeon),there's Stealth Rock,Spikes,Toxic Spikes,and finally,you could be put to sleep by Poli's Hypnosis.
No matter how you look at it,if you're forced to use a mon from an incredibly small list(What is it,like 3 viable ones?),something's wrong.
Any other weather checks rain, with abomasnow completely manhandling it. Water absorbers also make excellent rain checks, although they can have trouble with kingdra and ludicolo. Kingdra itself is an excellent pokemon and check and carrying one and getting it in on a quad resisted water attack can give oyu a chance to set up and really hurt their team. I think you're underestimating what can check it. It's still not a very long list, admittedly.