Abomasnow might be known as anti-weather but Abomasnow is not all about being anti-weather and therefore is still a very viable Pokémon.
Take a closer look at Abomasnow and you'll see it's just like your other OU viable grass type:
It's attacking stats are pretty average but with STAB moves even stronger than Earthquake, Abomasnow can and will hit like a truck. It even hits at both side of the spectrum, which is pretty neat. Its Speed stat is pretty low, which can be bothersome sometimes.
It's physical defense is pretty average but it's not much of an issue as Abomasnow has specially based resistances, not physical. Speaking of Sp Bulk, 90/85 is pretty good, for comparison, it's almost equal to the well-known Sp Wall, Zapdos.
Now it looks like Abomasnow is just a subpar grass type, but Abomasnow's unique typing, along with its unique movepool(and ability!) that no other Pokémon posses, makes it perfectly viable in the tier and is no gimmicky.
Obamasnow is part Ice, this is actually a huge boon for Obamasnow as it allows it to threaten grass types that attempt to stop his SubSeeding or to be not weak to Water-types' ever common Ice type coverage. It's Ice typing also means that Abomasnow can threaten those pesky Dragons who tend to switch-in on other Grass types used in OU. The only real downside of Ice typing is the weakness to Rock, which means...
The problem with most people is that they treat Abomasnow as an anti-weather and/or as an Ice type. This is correct, but wrong too, I'll justify why.
Abomasnow is anti-weather but should not be played as such because Abomasnow requires dedicated team support, it's not like when you're struggling against weather teams, you slap in Abomasnow, it won't work. Rather, Abomasnow should be played as a weather inducer itself. Like I said, Abomasnow needs a dedicated crew just like other weather inducers. Hail might have no real abusers, but a Hail team use Hail to take advantage of having no boosting weather in play and having residual damage every turn, if you're NOT using hail for this reason, you're using it incorrectly.
Abomasnow is an Ice type but should not be played as such. Rather, it should be played as (the bane of Water-type) a Grass-type. Switching on Electric/Water/Ground/Grass attacks is what a grass type does and then proceed to deal some damage obv. When dealing with Water types, Abomasnow nerfs the possible rain and is not weak to Ice, giving it an edge in the competition.
Another misconceptions are that people treat Hail as another weather to abuse or poor hail no abusers and Abomasnow is frail. Hail is a very neutral weather, "Rain boosts Water and debuffs Fire and Sun..." it's very obvious that hail is not meant to be abused. Sand also falls on the same boat, with Ttar and the few Sand Rush/Force being the only real "abusers". People also say Abomanow is 'frail' or dies easily because of its many weaknesses, but Grass types always had a lot of weaknesses ; Grass type offer great resistances but many weaknesses(2 are uncommon) and therefore, should be played with care. No, StallRein sucked in GenV OU.
Abomasnow's Mega Form is pretty good too, and no, it's not only limited to TR sweeping. Mega Abomasnow can be also played like a 'Bulky Band/Specs'. Switch in on something that can't threaten you or is witlessly scared, and deal massive damage to whatever switches in. Mega Abomasnow lacks a boosting item but makes up for it by having high-powered STABs, being able to hit in both sides, and the ability to switch moves(most common scenario of switching moves is hitting the switch-in and finishing it with Ice Shard).
tl ; dr, Abomasnow is still very viable.
