This is my first competitive team, so I just wanted some input on it, it's for my third gen games. I'm open to any constructive criticism.
I decided to make it, for a few reasons, the first is, I can't even get through the first few levels of Orre Colosseum in Pokemon XD, and the Battle frontier in both emerald and Platinum. the second is I recently battled a friend, and they kicked my @ss like it was nothing. I knew I was more bark than bite, but that was ridiculous. The final reason is I've been into the Pokemon games for a while now, and I've never done this before, and I thought it might be interesting to try out competitive battling.
Special Sweeper
Alakazam @ Twisted Spoon
Trait: Synchronize
Max IVs: Special attack/Speed/Defense
EVs: 252 Special attack/129 speed/ 129 Defense
Nature: Modest
~ Psychic
~ Calm Mind
~ Thunder Punch
~ Ice Punch
It seems like if a Pokemon is a strong attacker, it also has a semi strong defense, and is semi weak in Special Defense, and vice versa so with Alakazam I decided to max out its special attack, but split the rest of it's EV's between it's speed and defense, figuring that if I send him out to attack a Pokemon that has a weak special defense, it will probably have a strong attack. If that makes sense. As for strategy, I pretty much just plan to attack with whatever works best, that's about it.
Physical Sweeper
Salamence @ ???
Trait: Intimidate
Max IVs: Attack/Speed/Special Defense
EVs: 252 Attack/129 Speed/129 Special Defense
Nature: Adamant
~ Double Edge
~ Earthquake
~ Fly
~ Dragon Dance
Salamance I am using as the opposite of my special sweeper, maxing out it's attack, and then splitting the rest of speed and special defense. My strategy is most likely going to be spamming double edge, when I was younger and playing through Pokemon XD gale of darkness, I remember fly being my best move so that's why I have it now.
Mixed Sweeper
Arcanine @ ???
Trait: Intimidate/Flash Fire (I'm torn, they're both good.)
Max IVs: Attack/Special Attack/Speed
EVs: 252 Attack/252 Special Attack/3 Defense/3 Special Defense
Nature: Serious/Hardy/Quirky/Docile/Bashful
~ Overheat
~ Sunny Day
~ Hyper Beam
~ Double Edge
If I think I can take a pokemon out with a single overheat, I probably won't bother using Sunny day. That's the closest to a strategy I've got, and because he is going to be both a physical and special sweeper, I plan max out both of his attack EV's and split the rest between the defenses
Wall
Ludicolo @ Leftovers
Trait: Rain Dish
Max IVs: Defense/Special defense/HP
EVs: 129 Defense/129 Special defense/252 HP
Nature: Bold
~ Rain Dance
~ Leech Seed
~ Gigga Drain
~ Toxic
with Ludicolo, I really wish that he learned baton pass, that would be awesome strategically. Rain dance upon sending the Pokemon out, leech seed, Toxic, and finally spam Gigga Drain.
Baton Passer
Smeargle @ Focus Band
Trait: Own Tempo
Max IVs: Defense/Special Defense/HP
EVs: 252 Defense/252 Special Defense/6 HP
Nature: Jolly/Timid
~ Ingrain
~ Bellydrum
~ Tail Glow
~ Baton Pass
Finally with Smeargle, I will max out his defense, hopefully so that he can survive a few hits. Using ingrain first, doing three tail glows, a belly drum, and then finally Baton Passing to one of my sweepers. I can skip Belly drum or Tail glow depending on the sweeper.
I still need another wall, this wall I need to last a few turns against both physical and Special opponents, basically it's going to be my anchor, my Pokemon cockroach in the event of a nuclear attack. I plan to max out defense everything on this Pokemon. My strategy would be to remain stocked in necessary items, and in the event that the rest of my team is wiped out, I can send him out last, and revive the rest of my team.
There are a few walls that I've heard a lot of good things about, them being:
Skarmory – unfortunatly its special defense stat is higher than it's physical stat, I would prefer something with more equal stats.
Blissy – I have heard great things about Blissy, but I've tested it a bit, and it was killed easily by Pokemon with strong physical attacks. Otherwise, I believe Blissy would be Perfect. If there is any way to bulk it up defensively, I would love to know.
Shuckle - I was thinking about using Shuckle, for it's amazing Defense stats, but the rest of its stats suck, including HP, so I really don't know what to do. That's about it.
I decided to make it, for a few reasons, the first is, I can't even get through the first few levels of Orre Colosseum in Pokemon XD, and the Battle frontier in both emerald and Platinum. the second is I recently battled a friend, and they kicked my @ss like it was nothing. I knew I was more bark than bite, but that was ridiculous. The final reason is I've been into the Pokemon games for a while now, and I've never done this before, and I thought it might be interesting to try out competitive battling.
Special Sweeper

Alakazam @ Twisted Spoon
Trait: Synchronize
Max IVs: Special attack/Speed/Defense
EVs: 252 Special attack/129 speed/ 129 Defense
Nature: Modest
~ Psychic
~ Calm Mind
~ Thunder Punch
~ Ice Punch
It seems like if a Pokemon is a strong attacker, it also has a semi strong defense, and is semi weak in Special Defense, and vice versa so with Alakazam I decided to max out its special attack, but split the rest of it's EV's between it's speed and defense, figuring that if I send him out to attack a Pokemon that has a weak special defense, it will probably have a strong attack. If that makes sense. As for strategy, I pretty much just plan to attack with whatever works best, that's about it.
Physical Sweeper

Salamence @ ???
Trait: Intimidate
Max IVs: Attack/Speed/Special Defense
EVs: 252 Attack/129 Speed/129 Special Defense
Nature: Adamant
~ Double Edge
~ Earthquake
~ Fly
~ Dragon Dance
Salamance I am using as the opposite of my special sweeper, maxing out it's attack, and then splitting the rest of speed and special defense. My strategy is most likely going to be spamming double edge, when I was younger and playing through Pokemon XD gale of darkness, I remember fly being my best move so that's why I have it now.
Mixed Sweeper

Arcanine @ ???
Trait: Intimidate/Flash Fire (I'm torn, they're both good.)
Max IVs: Attack/Special Attack/Speed
EVs: 252 Attack/252 Special Attack/3 Defense/3 Special Defense
Nature: Serious/Hardy/Quirky/Docile/Bashful
~ Overheat
~ Sunny Day
~ Hyper Beam
~ Double Edge
If I think I can take a pokemon out with a single overheat, I probably won't bother using Sunny day. That's the closest to a strategy I've got, and because he is going to be both a physical and special sweeper, I plan max out both of his attack EV's and split the rest between the defenses
Wall

Ludicolo @ Leftovers
Trait: Rain Dish
Max IVs: Defense/Special defense/HP
EVs: 129 Defense/129 Special defense/252 HP
Nature: Bold
~ Rain Dance
~ Leech Seed
~ Gigga Drain
~ Toxic
with Ludicolo, I really wish that he learned baton pass, that would be awesome strategically. Rain dance upon sending the Pokemon out, leech seed, Toxic, and finally spam Gigga Drain.
Baton Passer

Smeargle @ Focus Band
Trait: Own Tempo
Max IVs: Defense/Special Defense/HP
EVs: 252 Defense/252 Special Defense/6 HP
Nature: Jolly/Timid
~ Ingrain
~ Bellydrum
~ Tail Glow
~ Baton Pass
Finally with Smeargle, I will max out his defense, hopefully so that he can survive a few hits. Using ingrain first, doing three tail glows, a belly drum, and then finally Baton Passing to one of my sweepers. I can skip Belly drum or Tail glow depending on the sweeper.
I still need another wall, this wall I need to last a few turns against both physical and Special opponents, basically it's going to be my anchor, my Pokemon cockroach in the event of a nuclear attack. I plan to max out defense everything on this Pokemon. My strategy would be to remain stocked in necessary items, and in the event that the rest of my team is wiped out, I can send him out last, and revive the rest of my team.
There are a few walls that I've heard a lot of good things about, them being:

Skarmory – unfortunatly its special defense stat is higher than it's physical stat, I would prefer something with more equal stats.

Blissy – I have heard great things about Blissy, but I've tested it a bit, and it was killed easily by Pokemon with strong physical attacks. Otherwise, I believe Blissy would be Perfect. If there is any way to bulk it up defensively, I would love to know.

Shuckle - I was thinking about using Shuckle, for it's amazing Defense stats, but the rest of its stats suck, including HP, so I really don't know what to do. That's about it.