My lead. For speed I know that I need to be slower than a Neutral speed Ttar so that if I come across a Ttar lead I get hail. At this point I have to kill the bastard so that it doesn't get the chance to ruin my hail.
Copy/Pasted from smogon. Hail Wall-rein. With toxic spikes support from Cloyster Roar is good for stalling enemies out much faster if the opportunity arises. Surf is filler.
Mamoswine@Choice Band (Snow Cloak)
Adamant (/Jolly?) - 252 Atk, 252 Speed, 6 HP
Earthquake
Ice Shard
Superpower
Bite
Ridiculous attack here. STAB EQ and STAB Ice Shard with priority. I picked bite as the last move in case of Psychics and ghosts, I think.
Pretty Standard. Takes damage from hail and life orb so I don't expect it to live long, but I'm hoping it'll damage things that my other pokes can't quite damage as well.
Physical wall. I'm not sure if the item clause will be present in the tournament I'm playing in, but if it's not I'll use leftovers. If not I'm not sure what I could use. Icy Wind seems like it would be useful to cripple stuff that would otherwise threaten me.
And I haven't decided on my 5th pokemon yet. I thought about Heatran to absorb fire damage that I'd take but I don't think I'd be able to work. Graciously accepting any and all criticisms and suggestions.
A few problems, how do you plan on killing the tyranitar? If you keep in abomasnow, then tyranitar will simply stone edge it. If you switch out, then l'd expect most people to switch out from tyranitar to a different pokemon. Walrein is good, l like brine on my Walrein, but personal preference. Mamoswine seems fine. Azelf seems counter-productive, l'd suggest starmie for rape and support or moltres for synergy (which is extremely important for hail teams) Replace cloyster with tentacruel or forretress for stronger stall and one less ice-water.
A simple solution to the item clause would be to switch Cloyster out for Tentacruel and use Black Sludge, but you lose the double spikes. You'll also be less weak to Scizor, and we all know we don't want a Scizor weak...(which your team has btw and no one can reliably take counter him).
I think Stone Edge would be a lot better on Mamoswine. It still does more damage than a SE Bite and you get better type coverage with EdgeQuake.