It's been a while since I tried to build a serious team, but here it is. (Also: it's a team for in-game (battle spot, battle tree, etc.), so tiers don't apply here.)
On a side note: Zoroark and Gengar have already been hatched and EV-trained, but the rest haven't yet. This means that I can't make changes concerning egg moves to those two.
Gliscor @ Toxic Orb
Careful nature
Poison Heal
252 sp.def/252 spe/4 def
-Stealth Rock
-Knock Off
-Taunt
-U-Turn
This would be my lead Pokemon. Stealth Rock is a pretty reliable hazard move. It will also have Taunt for if the opposing Pokemon tries to set up, and Knock Off for if it's a set that relies on items. U-turn is to switch out once Gliscor is done setting up and crippling the opponent.
Zoroark @ Choice Specs
Timid nature
Illusion
252 sp.atk/252 spe/4 HP
-Extrasensory
-Dark Pulse
-Flamethrower
-Focus Blast
Zoroark is a special sweeper. Since this set uses the choice specs, set-up moves aren't an option, and instead I gave him a moveset with focus on power and type coverage. I also used his illusion ability to my advantage (elaborated on with the next Pokemon).
Gengar @ Gengarite
Timid nature
Cursed Body/Shadow Tag
252 sp.atk/252 spe/4 HP
-Psychic
-Sludge Wave
-Will-O-Wisp
-Hex
Like Zoroark, Gengar is a special sweeper. Cursed Body is used with Will-O-Wisp to burn and trap an opposing Pokemon (and as a bonus, it halves the opponent's attack, which makes up in part for Gengar's mediocre defense). With the burn, Hex will then double in power. Sludge Wave and Psychic are for coverage. Gengar is also used for Zoroark's illusion ability, since it discourages fighting, fairy, and bug-type moves.
Golisopod @ Assault Vest
Adamant nature
Emergency Exit
124 HP/252 atk/132 sp.def
-Leech Life
-Poison Jab
-First Impression
-Aqua Jet
Golisopod is a physical tank, with the ability to both take hits and do damage. Leech Life allows it to recover health when necessary, Poison Jab is just a fairly powerful move, and the other two are decent STAB attacks with priority.
Tyranitar @ Choice Band
Adamant nature
Sand Stream/Unnerve
200 HP/252 atk/52 sp.def
-Stone Edge
-Earthquake
-Crunch
-Ice Punch
Since Tyranitar also has a choice item, I focused its moveset on coverage, with some powerful STAB moves. Like Golisopod, it will be a physical tank. I could also alter this to be a physical sweeper, but Tyranitar doesn't have nearly enough speed.
Metagross @ Leftovers
Careful nature
Clear Body
252 HP/252 atk/4 sp.def
-Meteor Mash
-Bullet Punch
-Thunder Punch
-Earthquake
Metagross effectively covers the last few holes in the team in terms of type weaknesses, while also being another physical tank. Bullet Punch is a priority STAB move, and Meteor Mash is a more powerful STAB move. Thunder Punch and Earthquake are there for coverage. Since it discourages fairy and bug-type moves, it can also be a backup for Illusion.
My main concern about this team is the lack of physical sweepers and special tanks. I don't know if that will be a problem or not, but for an offensive team, it might be good to have more variety. I'm also not certain whether Metagross and Gliscor's sets are the best they can be.
On a side note: Zoroark and Gengar have already been hatched and EV-trained, but the rest haven't yet. This means that I can't make changes concerning egg moves to those two.
Gliscor @ Toxic Orb
Careful nature
Poison Heal
252 sp.def/252 spe/4 def
-Stealth Rock
-Knock Off
-Taunt
-U-Turn
This would be my lead Pokemon. Stealth Rock is a pretty reliable hazard move. It will also have Taunt for if the opposing Pokemon tries to set up, and Knock Off for if it's a set that relies on items. U-turn is to switch out once Gliscor is done setting up and crippling the opponent.
Zoroark @ Choice Specs
Timid nature
Illusion
252 sp.atk/252 spe/4 HP
-Extrasensory
-Dark Pulse
-Flamethrower
-Focus Blast
Zoroark is a special sweeper. Since this set uses the choice specs, set-up moves aren't an option, and instead I gave him a moveset with focus on power and type coverage. I also used his illusion ability to my advantage (elaborated on with the next Pokemon).
Gengar @ Gengarite
Timid nature
Cursed Body/Shadow Tag
252 sp.atk/252 spe/4 HP
-Psychic
-Sludge Wave
-Will-O-Wisp
-Hex
Like Zoroark, Gengar is a special sweeper. Cursed Body is used with Will-O-Wisp to burn and trap an opposing Pokemon (and as a bonus, it halves the opponent's attack, which makes up in part for Gengar's mediocre defense). With the burn, Hex will then double in power. Sludge Wave and Psychic are for coverage. Gengar is also used for Zoroark's illusion ability, since it discourages fighting, fairy, and bug-type moves.
Golisopod @ Assault Vest
Adamant nature
Emergency Exit
124 HP/252 atk/132 sp.def
-Leech Life
-Poison Jab
-First Impression
-Aqua Jet
Golisopod is a physical tank, with the ability to both take hits and do damage. Leech Life allows it to recover health when necessary, Poison Jab is just a fairly powerful move, and the other two are decent STAB attacks with priority.
Tyranitar @ Choice Band
Adamant nature
Sand Stream/Unnerve
200 HP/252 atk/52 sp.def
-Stone Edge
-Earthquake
-Crunch
-Ice Punch
Since Tyranitar also has a choice item, I focused its moveset on coverage, with some powerful STAB moves. Like Golisopod, it will be a physical tank. I could also alter this to be a physical sweeper, but Tyranitar doesn't have nearly enough speed.
Metagross @ Leftovers
Careful nature
Clear Body
252 HP/252 atk/4 sp.def
-Meteor Mash
-Bullet Punch
-Thunder Punch
-Earthquake
Metagross effectively covers the last few holes in the team in terms of type weaknesses, while also being another physical tank. Bullet Punch is a priority STAB move, and Meteor Mash is a more powerful STAB move. Thunder Punch and Earthquake are there for coverage. Since it discourages fairy and bug-type moves, it can also be a backup for Illusion.
My main concern about this team is the lack of physical sweepers and special tanks. I don't know if that will be a problem or not, but for an offensive team, it might be good to have more variety. I'm also not certain whether Metagross and Gliscor's sets are the best they can be.