Introduction
This is a very simple team based heavily on offense and speed. I personally struggle to break through 1500, but this happens with every team for me as I am not that great. That being said, I have typically the most success with this team, and I would love to see what a more skilled player could do with it!
The Team
Zygarde is the most bulky Pokemon on the team and is a great utility against steel types. If I can manage a good switch-in and a coil or two he can often take down 2+ pokemon. Thousand arrows is extremely useful against flying types. Extreme speed after coil can typically take down most glass cannons and sweepers such as Greninja. Substitute can cause serious problems for an opponents defensive pokemon once his defense has been boosted.
Kartana with a choice band and variety of move types offers extremely high chances of a one hit KO. Very cut and dry. Once beast boost comes into play it's just a matter of your speed vs your opponents. I have taken down 5+ with him many times. STAB moves like steel strike and leaf blade are preferred but often not necessary after the bonus attack from the choice band.
Weavile is an excellent utility against dragon, psychic, and ground types primarily. His high speed allows him to easily clean up weaker types following a fake out.
This is a risky build that I really enjoy. With focus sash, speed is often not a factor. Against a faster pokemon I can often use quiver sash, then survive one turn. After that, speed is boosted higher than any pokemon default with the exception of those using choice scarves (even then, 448 speed is very competitive). Fiery dance is a preferred move to use after this, as the potential SpA boosts are extremely beneficial. Timed correctly, volcarona frequently can beat 2+ pokemon.
I use Nihilego more as support. I find him to be a safe lead given the focus sash and moveset. Thunder wave is very useful against difficult and bulky Pokemon. Stealth rock is always very useful to nullify opponents focus sashes and heavily damage fire, flying, and bug types etc. Nihilego is also very versatile as beast boost can sometimes lead him to many kills.
I consider Alakazam my safety net. His moveset and SpA allows him to contend with most pokemon. Dazzling gleam is excellent to have for dragon and dark types. Without STAB, it still frequently one hit KOs. His Energy Ball is probably the best counter to water types even surpassing Kartana. He's a total glass cannon but is often good for at least a kill.
Conclusion
The team is really built around speed and damage. The focus sashes allow for many second chances that I find often result in crucial kills. There isn't much room for switching around given the low HPs and defenses. Zygarde is the only one I feel comfortable switching in usually. With this team I find all it takes is one pokemon to catch fire with stat boosts and they can easily disrupt or take down a whole team.
Please let me know what you think and I would really appreciate more feedback from someone who tries it!