The particular spread you mentioned works as a Special Attacking and Tank Abomasnow.
The 4 EVs in attack are to power up Ice Shard, its only means of priority.
You basically put most EVs (usually max i.e 252) on a stat you think is gonna be the most useful or productive. For example we have a Weavile.
If you take a glance at its base stats, you see that it has high speed and attack stats. So that's where you have to invest EVs.
Here are some major roles that a Pokemon can take for it's team:
Wall: A Pokemon that can take hits for the team and play stall/mind games. They also usually carry status and/or entry hazards. Eg.- Shuckle, Blissey. They run EVs in defenses so that they can take hits better.
Sample Spread: 252 HP / 252 Def / 4 Sp.Def
Sweeper: A Pokemon that can go on the offense for your team. They tend to carry strong attacking moves and/or set-up moves to increase their offenses. Eg.- The mentioned Weavile, Garchomp. They run investments in their higher attacking stats and speed, so that they can outspeed other Pokemon and get in a hard hit which can, either severely dent or knock out the opposing Pokemon.
Sample spread: 252 Atk / 252 Spe / 4 HP
Tank: These Pokemon are a cross between a Wall and a Sweeper, where they are bulky and hard hitting at the same time. The usually carry moves that are suitable to their main cause, like the Abomasnow runnning 4 attacks and an Aggron running 3 attacks and one status/hazard move. They usually run investments in their HP and attack stats, so that their offense and defense are somewhat in equilibrium.
Sample spread: 252 Sp.Atk / 252 HP / 4 Def (or attack in Abomasnow's case)
Wallbreakers: These Pokemon are almost tailor made to destroy opposing walls from doing mischief. They lack the potential to sweep, and usually don't have good bulk, usually characterised by sky high offenses. Many can also become sweepers if given the chance. Eg. - Breloom, Scrafty. They usually invest in their offense stat and another stat that might be beneficial.
Sample spread: 252 Atk / 164 Spe / 92 HP
Those are the major roles, there are many sub roles like Rapid Spinner, Hazard Setter, Pivot etc. but they can all be classified into these groups in my opinion.
However, Pokemon can do different roles from what their stats suggest as well. Like Gyarados, while it goes for high attack usually, it can potentially run a tankier set, due to its good typing. In which case, it will run HP investments more than attack.
It actually takes a while.to understand which Pokemon does what best, but when you know what job it does well, like for a Weavile, you know where to invest.
With respect to Super Training:
In super training, there are the following regimens that are built for EV training purposes:
- Super Training level 1: (all stats are raised by 4 EVs here)
a] Magnemite (Special Attack)
b] Wailmer (HP)
c] Axew (Attack)
d] Tentacool (Special Defense)
e] Noibat (Speed)
f] Geodude (Defense)
- Super Training level 2: (all stats are raised by 8 EVs here)
a] Magneton (Special Attack)
b] Relicanth (HP)
c] Fraxure (Attack)
d] Tentacruel (Special Defense)
e] Aerodactyl (Speed)
f] Graveler (Defense)
- Super Training level 3: (all stats are raised by 12 EVs here)
a] Magnezone (Special Attack)
b] Wailord (HP)
c] Haxorus (Attack)
d] Dragalge (Special Defense)
e] Noivern (Speed)
f] Golem (Defense)
You can use these for minute detailing in EVs, like 128 Atk.
Source: Basic knowledge on EVs and my DS
Hope I helped!