Legendary Pokémon

Ok, I was looking through the ultimate team stuff and I noticed there should be some stuff to bear in mind:

Gold/Silver/Crystal Poliwrath

Can learn easily the best combo in the game, tie them in with whirlpool, aim with mind reader, kill them with fissure and if they're a flying type thunder will do the trick.

Paralyse then switch combo

Something along the lines of thunder wave then whirlwind is an amazing and annoying way to hurt you enemies.

Magicness then attack

Combos such as sunny day and solarbeam are there to be used, c'mon people!

Weakness, what weakness?!

Use a Pokémon's dual type to get it down to one weakness! Usually this is a super effective x 2 weakness, but still, less things to kill it!

Bang, bang, boom!

Explosion or self destruct?! Well, if you max out a Pokémon's attack and make sure it is really strong AND give it a focus band then hey, you can do some damage!!! (And if you're lucky you'll live!)

Ditto and smeargle

Are not cool. Don't be tempted by them because they seem magic! They have like -4050304444 stats.

Always have something to fight back with!

If you're a ground type then have a thunder move, a water type then something to kill electric or grass. You see the point, a last ditch super effective attack is far more use than using something like surf on a Venusaur.

Be very annoying

Lock your enemy in with a move that stops switching then poison them, then confuse them, then start a sand storm. Now just keep defending, a wake up item and rest maybe? Stuff along those lines! If you can make them miss a few attack turns then even better! They'll die from slow HP loss! Obviously this isn't the best plan 100% of the time, but against real strong critters it can be useful! Try to make sure the 'mon that does this has high defence and special defence.

Male or female?

Think about stats! Do you need power? Or defence? That makes a big difference!

Magic rock Moola!

Use items wisely, leftovers attached to a high defence 'mon can be fun!

Team doesn't work?!

Don't have a team consisting of Tyranitar, Mewtwo, Alakazam, Mew, Gengar and Misdreavus because you feel cool and powerful, it just doesn't cover enough possibilites! (And you Gamesharked the Mew!!!)

This is all I can think of off the top of my head, but if I think of some real killer combos (or make some example 'mon) then I'll let you know! Basic stuff, but many a time overlooked!

I hate it when others use teams like: Rayquaza, Kyogre,Groudon,Latios,Latias and Deoxys.
My team is: (emerald)
Ninjask-Baton Passer
-Sword dance
-double team
-baton pass
-silver wind

Dusclops-Annoying
-Curse
-Toxic
-Confuse Ray
-Mean Look

Sceptile-Sweeper
-Leaf Blade
-Slam
-Pursuit
-Fury Cutter

Shuckle-Tank
-Rest
-Snore/Sleep Talk
-Bide
-Double Team

Metagross-Physical Sweeper
-Hyper Beam
-Meteor Mash
-Double Team
-Iron Defense

Latias-Element
-Surf
-Thunder Bolt
-Ice Beam
-Psychic

And what's good about a Misdreavus

I would suggest not to use mixed sweepers.I would also suggest Toxic on Shucle and Rest on Dusklops

I think I'll change Sceptile in Gardevoir, *there's a stupid fly flying around me*, what happens if you use Gardevoir against a Castform (so you also get Fore Cast) and he uses Sunny Day?

You are just considered to be a Fire Type... That is if you have the Trace ablity...

ow... and Dusclops' item is Leftovers

A good choise but it still needs rest.After all three night shades can defeat it.Or you can use pain split instead but it is a little risky.I use both rest and pain split along with mean look and either will o whisp or curse...

I love grass pokémon, so let me give you an advise on Sceptile: Since it's defences are low, don't use Fury Cutter. Slam isn't that good and haven't accuracy, too. Replace these moves with Dragon Claw and Detect. Pursuit is good only when the foe is switching. If you replace it with Toxic, baton pass some double team from Ninjask and your Sceptile is gonna be hard to defeat.
Don't use Bide on Shuckle, it's HP is horrible and, like Counter, Bide does damage depending on the number of HP lost. Why don't use Toxic and Wrap? If it helps you, my Shuckle has Sandstorm, Wrap, Toxic and Rest.

i wouldn't recomend using dragon claw with sceptile. one of mine has crush claw. thouge it has poorer attack power and accuracy, it has a 50% chance of lowering defence, making it more powerful over time. i do respect your choice of attacks though.

The only problem using crush claw, is that you may need to put some effort points in atk. If you use Sceptile as a special sweeper, though, you'll max them in satk and spd.

mine has a lonly nature, making its attack almost as good as its spa. and sceptile has one of the highest spa of grass types

But if you use a modest or timid nature, you may use better Sceptile's satk and speed without losing defence (which is already bad).
It's not good to use mixed sweepers, as Blue said...

i dont use it as a mixed sweeper. i just have crush claw b/c there are those out there who have sp. de better than defence with excellent attack. and i kind of have my own battle style. most of my teams are composed of sweepers, mainly mixed. and besides, whats so bad about having a mixed sweeper. blaziken and cacturne make great mixed sweepers. my sceptile knows false swipe , for those pokemon im planning on capturing, crush claw, leaf blade, and giga drain. and from the rest of my team and their types, i need not worry about the opponents pokemon. i have never lost, and dont plan on doing so. and you dont really have to worry about defence so much, seeing that sceptile has a variety of moves.sceptiles attack is particularly high, seeing that most grass types dont have very good attack, so a rock tomb could take out most of a flying types hp or even ko it and bug types dont usually have good defences.

If you think... I respect, but if you play with more expert people, you may lost.

Having a mixed sweeper means that you have to spread the Eps to both attack and sp Attack and that means that you can't have a really good attacking stat.