Hey, so I'm kinda new to this whole competitive battling thing, because I easily laugh at my friends' teams, so I decided to come here and try and get advice. BTW: I'm terrible at making EV spreads so I could use help with that. Edits in bold
Making the team:
So, I started out with Rhyperior, because he is a pure beast.

Then, I looked at all of Rhyperior's weaknesses and saw that a Water-Flying type would greatly help, being resistant to Water, Steel, Fighting and Ground. Sadly, Gyarados is an OU Pokemon, so I had to pull up either Mantine or Pelipper from NU. I hate Pelipper, so Mantine it is
After that, I realized that this works out quite well, due to Rhyperior's high defense and Mantine's high special defense. So, I started working on offense. Rhyperior pairs well with grass types, so I chose Venusaur, who can deal a good amount of damage.
Seeing as I had a water and grass type, I said, "Might as well," and added Houndoom to complete the FWG.
So, now that I finished the offensive and defensive cores, I decided to make a lead. The lead needed Stealth Rock, so that my Pokemon could get kills easier. I also needed a pokemon that could take a physical fighting type attack. I chose Uxie for this role, because he's quite bulky, relatively fast and can lay SR.
For the last spot, I decided to have a status inflicter for support. Seeing as Rotom could do this and block Rapid Spin, he claimed the final spot.


After that, I realized that this works out quite well, due to Rhyperior's high defense and Mantine's high special defense. So, I started working on offense. Rhyperior pairs well with grass types, so I chose Venusaur, who can deal a good amount of damage.



Seeing as I had a water and grass type, I said, "Might as well," and added Houndoom to complete the FWG.




So, now that I finished the offensive and defensive cores, I decided to make a lead. The lead needed Stealth Rock, so that my Pokemon could get kills easier. I also needed a pokemon that could take a physical fighting type attack. I chose Uxie for this role, because he's quite bulky, relatively fast and can lay SR.





For the last spot, I decided to have a status inflicter for support. Seeing as Rotom could do this and block Rapid Spin, he claimed the final spot.






In-Depth:
Uxie @ Leftovers
Levitate
Impish, 252 HP/4 Atk/252 Def
-Stealth Rock
-U-Turn
-Yawn
-Zen Headbutt
Mantine @ Leftovers
Water Absorb
Calm 252 HP/252 Spd/4 Spe
-Surf
-Rest
-Sleep Talk
-HP Flying
Houndoom @ Life Orb
Flash Fire
Hasty, 4 HP/96 Atk/156 SpA/252 Spe
-Nasty Plot
-Flamethrower
-Dark Pulse
-Sucker Punch
Rotom @ Leftovers
Levitate
Timid, 252 SpA/4 SpD/252 Spe
-Discharge
-Will-o-Wisp
-Toxic
-Shadow Ball

Uxie @ Leftovers
Levitate
Impish, 252 HP/4 Atk/252 Def
-Stealth Rock
-U-Turn
-Yawn
-Zen Headbutt
So, the lead. Uxie was chosen because it can set up SR, psuedo haze, and be a somewhat-effective wall. This is the basic support Uxie with a pretty simple EV spread. I chose Yawn over Thunder Wave because of a: it has good synergy with SR and b: Rotom can already paralyze. The offensive moves are only resisted by steel types, which the rest of my team has no problem dealing with.

Rhyperior @ Leftovers
Solid Rock
Adamant, 132 HP/192 Atk/16 SpD/168 Spe
-Substitute
-Swords Dance
-Earthquake
-Stone Edge
Solid Rock
Adamant, 132 HP/192 Atk/16 SpD/168 Spe
-Substitute
-Swords Dance
-Earthquake
-Stone Edge
So, the reason I made this team, kinda. Rhyperior is my main physical wall. Its massive HP gives it 101 Subs, which is quite helpful. Swords Dance boosts Rhyperior's already good attack even higher. I chose SD over another attacking move because EdgeQuake already has great type coverage in UU. Sadly, Rhyperior doesn't get a much needed Sandstorm boost, so his special defense is quite lacking.

Mantine @ Leftovers
Water Absorb
Calm 252 HP/252 Spd/4 Spe
-Surf
-Rest
-Sleep Talk
-HP Flying
The special wall arrives. Mantine's great special defense and good synergy with Rhyperior made it a good choice. Water Absorb can be of use when switching from Rhyperior or Houndoom. Surf and HP Flying are the basic STAB options for Mantine. Rest and Sleep Talk are for maximum durabilty.
Venusaur @ Life Orb
Overgrow
Jolly, 252 Atk/4 Def/ 252 Spe
-Synthesis
-Sleep Powder
-Power Whip
-Earthquake

Venusaur @ Life Orb
Overgrow
Jolly, 252 Atk/4 Def/ 252 Spe
-Synthesis
-Sleep Powder
-Power Whip
-Earthquake
Venusaur is my physical attacker. His main job is to severely weaken the team. Venusaur accomplishes this through LO'ing the hell out of them and then healing the recoil through Synthesis. Pretty simple...

Houndoom @ Life Orb
Flash Fire
Hasty, 4 HP/96 Atk/156 SpA/252 Spe
-Nasty Plot
-Flamethrower
-Dark Pulse
-Sucker Punch
Houndoom, the special attacker. It uses Nasty Plot to gain a lot more power. Flamethrower and Dark Pulse are the basic STAB moves. Sucker Punch is for Dugtrio that try to come in. I took Ev's out of SpA because Houndoom always wants max speed. Life Orb is to give that extra power.

Rotom @ Leftovers
Levitate
Timid, 252 SpA/4 SpD/252 Spe
-Discharge
-Will-o-Wisp
-Toxic
-Shadow Ball
Rotom, the final member of the team. Rotom is very useful, crippling many annoying pokemon. Obviously, Discharge is chosen over Thunderbolt for higher paralysis. Will-o-Wisp and Toxic are effective in weaking walls that would try to stop me. Shadow Ball is chosen over another status move to give Rotom more coverage.
Thank you for reading this! Please give feedback. I need some help with this.