I really like NU. I just started NU about a week ago, after struggling and failing to master OU, and my team has been met with mild success. Sometimes I pull through, other times I get butt raped by tactics I wouldn't have predicted in a million years. Regardless, I really like the meta, and I hope to improve. This being my first team, it may not be the greatest, but I really like the way it plays, so any advice on improving it is much appreciated!
Leavanny
Item: Focus Sash
Ability: Overcoat
EVs: 248 HP / 8 Atk / 252 Spe
Jolly Nature
Moves: Sticky Web, Leaf Blade, Toxic, Knock Off
Let's face it, you knew what this thing was used for before you even saw its moveset: Sticky Web. But, while it may be crammed down into PU, it makes a surprisingly good suicide lead. It's helped me out a lot, especially because my team is relatively slow bar two Pokemon, and one of those is just fast so it can Trick a scarf. It's sashed is so that it can survive at least one hit in order to lay down Web, as it is blatantly easy to OHKO it with the right move otherwise. It's Ability is honestly the only good thing I could think to put on it, because none of its three Abilities really fit its role as a suicide lead, except maybe Swarm, however Swarm is useless because I don't run any Bug-type moves. EVs let it take a hit given that the foe isn't Fire or Flying, and when they're not using these types it can actually take a surprisingly hard blow. Max speed lets it outpace most competing hazard setters or early game set ups. Leaf Blade is my main attacking move, and is used when there's nothing else left to be used. Toxic is for when walls are sent in, which Leavanny can't touch due to utter un-investment in attack. Knock Off helps cripple Pokemon who rely on items, especially those with scarves or Leftovers. As with all suicides leads however, it often only gets to use two or three of these moves before quickly dying.
Kangaskhan
Item: Assault Vest
Ability: Scrappy
EVs: 252 HP / 200 Atk / 56 SpD
Adamant Nature
Moves: Body Slam, Drain Punch, Fake Out, Ice Punch
While not exactly a staple member of my team, Kanga has definitely pulled me out of some unpleasant situations. With its great HP, usable attack, and an AV stapled on it makes a good tank for special threats, especially Magmortar. It's HP also allows it to take a few hits from physical attackers as well, though generally Kanga isn't used to deal with these kinds of threats unless it is already out. It can also do some good damage too, while keeping alive with Drain Punch recovery. Scrappy helps me deal with the occasional Ghost-types who can give me a hard time if I'm unprepared. EVs give me good bulk while still doing respectable damage, and Adamant nature adds onto attack for extra damage. Body Slam is chosen over Return for the 30% chance to paralyze. Drain Punch is used for recovery on account of the lack of Leftovers or Rest, along with the nice Fighting-type coverage it provides. Fake Out is there for obvious reasons, because a free flinch is always nice, as well as breaking sashes. Ice Punch is there for coverage, and helps a lot with the numerous threats in the tier that are weak to Ice, which is why it's chosen over Thunder and Fire.
Xatu
Item: Choice Scarf
Ability: Magic Bounce
EVs: 248 HP / 8 SpD / 252 Spe
Timid Nature
Moves: Thunder Wave, Wish, Trick, Night Shade
Xatu is probably one of the most important parts of my team. It is my answer to most walls, and is the reason I can afford not to have a Rapid Spinner on my team. Without it, and I was without it when I first made my team, I would have a much harder time handling all the things my offensive Pokemon get walled and stalled by. Scarf is mainly for Tricking, though sometimes I keep it on if I know I can just KO the opponent with Night Shade. Magic Bounce is my bread and butter, and is the main reason I have Xatu. It shines its brightest when I can switch in and reflect Toxic back, but it is also a solid answer to opposing Leavanny and Stealth Rock setters. EVs maximize its usage, HP giving it decent bulk and speed to ensure that even without a scarf it can go relatively fast. It hits an okay 317 speed with Timid nature, and is usually even faster with web support to slow down foes. Thunder Wave is usually a great follow up to Trick, essentially cancelling out the scarf and rendering the foe locked into a move with no benefits. Wish, while not great for Xatu itself, is good for team support, namely Audino and Kangaskhan, who often need the HP. Trick has already pretty much been explained, but I'll explain it again: passing my scarf to a foe who needs to be versatile or has an item that defines its niche lets me stop many foes who would otherwise love to set up on my more offensive Pokemon. Night Shade is a reliable move and preferred because of Xatu's lack of offensive investment. It's only drawback is that Normal-types are immune to it and can give Xatu a hard time, especially if it didn't Trick its scarf off and is locked into that move.
Audino (Mega)
Item: Audinite
Ability: Healer (The best Ability ever imo should be banned to AG)
EVs: 252 HP / 168 Def / 88 SpD
Bold Nature
Moves: Calm Mind, Dazzling Gleam, Hyper Voice, Psyshock
I've always had a soft spot for Audino. Partially because it has such a damn cute mega, and also because it's the only Gen V mega. Does Gamefreak hate that generation or something? Mega Serperior please and thank you. BW love aside, this is another important member of my team, who I value for its ability to take hits then dish them back out. If given even one turn to set up, this thing can tear right through Pokemon. EVs maximize its bulk, and with an already decent HP and defenses that shoot up after Mega Evolving, it can take most hits like a punching bag, with the exception of Poison Jab and Iron Head. Bold nature furthers its defense while CM is relied on to patch up its SpD. Calm Mind itself is what makes it so good at wrecking things once it has a few boosts, while also making it a great special wall. Usually 2 boosts are what it needs to become a hard hitter, but 1 can suffice if put under pressure. Dazzling Gleam is one of my main STAB moves, and believe me, I really wanted to put Draining Kiss here. I mean I REALLY wanted to. But more often than not I needed the damage more than the recovery, so I opted for a more powerful attack. Hyper Voice is my second STAB move, and hits hard. It also passes Subs, which even won me a battle once. Psyshock is for Poison-types who threaten Audino, as well as when a special wall is sent in to stop it.
Samurott
Item: Life Orb
Ability: Torrent
EVs: 120 HP / 252 Def / 136 SpD
Adamant Nature
Moves: Swords Dance, Aqua Jet, Megahorn, Waterfall
I didn't always have Samurott, but when I added him to my team, I was so glad I did. While the physical varient isn't as common as special, this set has helped me many times in many ways. It is my source of raw power and is my best revenge killer. Life Orb boosts its attack even further. EVs and nature maximize its attack while still outpacing some slower threats. Swords Dance is the move on this set that makes physical Samurott so good, boosting its attack to an amazing 656 after just one boost. Aqua Jet is mandatory priority because even with some investment in speed, it's often too slow to take down fast threats that would kill it first. Megahorn is just a good move in general and it gives me nice coverage, especially over Grass-types who would hassle me. Waterfall is my main STAB and does good damage with a Swords Dance behind it.
Mismagius
Item: Life Orb
Ability: Levitate
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
Moves: Dazzling Gleam, Destiny Bond, Taunt, Shadow Ball
Last but certainly not least is Mismagius. If there's one Pokemon on my team with amazing utility, it's this one. Since Leavanny usually barely survives turn one, let alone survive to lay down another web, this is my spin blocker. And since nothing else on my team has Taunt, this is also how I shut down set ups. It's also a part-time sweeper with Life Orb. EVs make it as fast and powerful as possible, with a respectable 105 speed that outspeeds a lot of the meta with a Timid nature. Dazzling Gleam is for Fighting and Dark-types that I can struggle with, especially if Audino is down by then. Destiny Bond is when all else fails and the opponent has managed to boost to dangerous levels, where I would rather have Mismagius die than let the foe tear my team to bits. Taunt is used to shut down a wide range of things, from sweepers who like to set up to stallers who try to use Subs or Toxic. Shadow Ball is my main stab and does good damage when I need it to, but is only used if I know I can go for the kill.
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So, that's my NU team. I'm still fairly new to it, but I feel like I have a good grasp, and any help for me to improve would be really appreciated! Even if I don't accept your advice I'm still grateful that you decided to give said advice.

Leavanny
Item: Focus Sash
Ability: Overcoat
EVs: 248 HP / 8 Atk / 252 Spe
Jolly Nature
Moves: Sticky Web, Leaf Blade, Toxic, Knock Off
Let's face it, you knew what this thing was used for before you even saw its moveset: Sticky Web. But, while it may be crammed down into PU, it makes a surprisingly good suicide lead. It's helped me out a lot, especially because my team is relatively slow bar two Pokemon, and one of those is just fast so it can Trick a scarf. It's sashed is so that it can survive at least one hit in order to lay down Web, as it is blatantly easy to OHKO it with the right move otherwise. It's Ability is honestly the only good thing I could think to put on it, because none of its three Abilities really fit its role as a suicide lead, except maybe Swarm, however Swarm is useless because I don't run any Bug-type moves. EVs let it take a hit given that the foe isn't Fire or Flying, and when they're not using these types it can actually take a surprisingly hard blow. Max speed lets it outpace most competing hazard setters or early game set ups. Leaf Blade is my main attacking move, and is used when there's nothing else left to be used. Toxic is for when walls are sent in, which Leavanny can't touch due to utter un-investment in attack. Knock Off helps cripple Pokemon who rely on items, especially those with scarves or Leftovers. As with all suicides leads however, it often only gets to use two or three of these moves before quickly dying.

Kangaskhan
Item: Assault Vest
Ability: Scrappy
EVs: 252 HP / 200 Atk / 56 SpD
Adamant Nature
Moves: Body Slam, Drain Punch, Fake Out, Ice Punch
While not exactly a staple member of my team, Kanga has definitely pulled me out of some unpleasant situations. With its great HP, usable attack, and an AV stapled on it makes a good tank for special threats, especially Magmortar. It's HP also allows it to take a few hits from physical attackers as well, though generally Kanga isn't used to deal with these kinds of threats unless it is already out. It can also do some good damage too, while keeping alive with Drain Punch recovery. Scrappy helps me deal with the occasional Ghost-types who can give me a hard time if I'm unprepared. EVs give me good bulk while still doing respectable damage, and Adamant nature adds onto attack for extra damage. Body Slam is chosen over Return for the 30% chance to paralyze. Drain Punch is used for recovery on account of the lack of Leftovers or Rest, along with the nice Fighting-type coverage it provides. Fake Out is there for obvious reasons, because a free flinch is always nice, as well as breaking sashes. Ice Punch is there for coverage, and helps a lot with the numerous threats in the tier that are weak to Ice, which is why it's chosen over Thunder and Fire.

Xatu
Item: Choice Scarf
Ability: Magic Bounce
EVs: 248 HP / 8 SpD / 252 Spe
Timid Nature
Moves: Thunder Wave, Wish, Trick, Night Shade
Xatu is probably one of the most important parts of my team. It is my answer to most walls, and is the reason I can afford not to have a Rapid Spinner on my team. Without it, and I was without it when I first made my team, I would have a much harder time handling all the things my offensive Pokemon get walled and stalled by. Scarf is mainly for Tricking, though sometimes I keep it on if I know I can just KO the opponent with Night Shade. Magic Bounce is my bread and butter, and is the main reason I have Xatu. It shines its brightest when I can switch in and reflect Toxic back, but it is also a solid answer to opposing Leavanny and Stealth Rock setters. EVs maximize its usage, HP giving it decent bulk and speed to ensure that even without a scarf it can go relatively fast. It hits an okay 317 speed with Timid nature, and is usually even faster with web support to slow down foes. Thunder Wave is usually a great follow up to Trick, essentially cancelling out the scarf and rendering the foe locked into a move with no benefits. Wish, while not great for Xatu itself, is good for team support, namely Audino and Kangaskhan, who often need the HP. Trick has already pretty much been explained, but I'll explain it again: passing my scarf to a foe who needs to be versatile or has an item that defines its niche lets me stop many foes who would otherwise love to set up on my more offensive Pokemon. Night Shade is a reliable move and preferred because of Xatu's lack of offensive investment. It's only drawback is that Normal-types are immune to it and can give Xatu a hard time, especially if it didn't Trick its scarf off and is locked into that move.

Audino (Mega)
Item: Audinite
Ability: Healer (The best Ability ever imo should be banned to AG)
EVs: 252 HP / 168 Def / 88 SpD
Bold Nature
Moves: Calm Mind, Dazzling Gleam, Hyper Voice, Psyshock
I've always had a soft spot for Audino. Partially because it has such a damn cute mega, and also because it's the only Gen V mega. Does Gamefreak hate that generation or something? Mega Serperior please and thank you. BW love aside, this is another important member of my team, who I value for its ability to take hits then dish them back out. If given even one turn to set up, this thing can tear right through Pokemon. EVs maximize its bulk, and with an already decent HP and defenses that shoot up after Mega Evolving, it can take most hits like a punching bag, with the exception of Poison Jab and Iron Head. Bold nature furthers its defense while CM is relied on to patch up its SpD. Calm Mind itself is what makes it so good at wrecking things once it has a few boosts, while also making it a great special wall. Usually 2 boosts are what it needs to become a hard hitter, but 1 can suffice if put under pressure. Dazzling Gleam is one of my main STAB moves, and believe me, I really wanted to put Draining Kiss here. I mean I REALLY wanted to. But more often than not I needed the damage more than the recovery, so I opted for a more powerful attack. Hyper Voice is my second STAB move, and hits hard. It also passes Subs, which even won me a battle once. Psyshock is for Poison-types who threaten Audino, as well as when a special wall is sent in to stop it.

Samurott
Item: Life Orb
Ability: Torrent
EVs: 120 HP / 252 Def / 136 SpD
Adamant Nature
Moves: Swords Dance, Aqua Jet, Megahorn, Waterfall
I didn't always have Samurott, but when I added him to my team, I was so glad I did. While the physical varient isn't as common as special, this set has helped me many times in many ways. It is my source of raw power and is my best revenge killer. Life Orb boosts its attack even further. EVs and nature maximize its attack while still outpacing some slower threats. Swords Dance is the move on this set that makes physical Samurott so good, boosting its attack to an amazing 656 after just one boost. Aqua Jet is mandatory priority because even with some investment in speed, it's often too slow to take down fast threats that would kill it first. Megahorn is just a good move in general and it gives me nice coverage, especially over Grass-types who would hassle me. Waterfall is my main STAB and does good damage with a Swords Dance behind it.

Mismagius
Item: Life Orb
Ability: Levitate
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
Moves: Dazzling Gleam, Destiny Bond, Taunt, Shadow Ball
Last but certainly not least is Mismagius. If there's one Pokemon on my team with amazing utility, it's this one. Since Leavanny usually barely survives turn one, let alone survive to lay down another web, this is my spin blocker. And since nothing else on my team has Taunt, this is also how I shut down set ups. It's also a part-time sweeper with Life Orb. EVs make it as fast and powerful as possible, with a respectable 105 speed that outspeeds a lot of the meta with a Timid nature. Dazzling Gleam is for Fighting and Dark-types that I can struggle with, especially if Audino is down by then. Destiny Bond is when all else fails and the opponent has managed to boost to dangerous levels, where I would rather have Mismagius die than let the foe tear my team to bits. Taunt is used to shut down a wide range of things, from sweepers who like to set up to stallers who try to use Subs or Toxic. Shadow Ball is my main stab and does good damage when I need it to, but is only used if I know I can go for the kill.
---
So, that's my NU team. I'm still fairly new to it, but I feel like I have a good grasp, and any help for me to improve would be really appreciated! Even if I don't accept your advice I'm still grateful that you decided to give said advice.