You also have to take items and abilities into account. Watching videos is good, knowing how much damage to expect and seeing more or less allows you to break down their set up, had to do it here,
CRMG-WWWW-WWW5-RPCJ, I threw together pokemon I liked and just went for it.

Yes: the first step is to determine a winning strategy. At that point, you conceive of it like building a deck in a TCG: what combinations of moves and monsters will win in most scenarios, or in the scenario you want to account for? (much of the metagame is mindgames, anticipating what strategy your opponent will choose as in, which *team* will they even choose).

The second step is, having chosen the Pokemon, getting the best possible Pokemon for that build, which involves IV selection and breeding and subsequent EV training.

The first step is easy-ish because there are a lot of common winning team combinations out there, so you can look at what others use and then use a variation of that which suits your interests. EV training has also been made super-easy for X and Y. IV breeding has been made SLIGHTLY easier because there's a mechanism to guarantee certain traits get passed on, though it's still far and away the most time-consuming part of it.

So
1) Choose your team on paper
2) IV-select and breed to get the best possible Pokemon for each species in that team.
3) EV-train and level up.

For a noob its simple.   Open up this page and look at the weakness/strong against each type.  http://www.serebii.net/xy/typechart.shtml

Grab any pokemon you like, don't worry about using the best, just choose ones you like.  Then teach them moves that are good that cover types.  Don't teach a fire pokemon ONLY fire moves.  Teach him some flying moves, psychic moves, ect.  Whatever he can that is also good.  

Look at the chart I posted again and see what types you are missing stil.  Don't have any water covered, find a pokemon you like that is either water type or can learn a good water move.

Just cover your bases basically.  Then start playing.  As you play you will adjust your team accordingly.  Whether you see the opponent do a move you found worked awesome, then teach it to someone on your team.  Or if you found out one of your moves just flat out sucks, remove it and teach new move.  If you find a pokemon you were using sucks, change it, or see a pokemon they using you liked, ect.  

But there is no quick road to pokemon champion.  But best start is to just cover your bases and then build from there.  You may end up with a nice diversified team or maybe you just go all out one type and rock the Sunny Day or other weather effects ect that improve your whole team.  

There is a ton you can do.  I hope you don't just copy/paste someone else's uber team.  The more variety on the online battles the funner the game.  No noe likes to see the same exact pokemon a million times or the same moves.

Worry about EV/IV/items later.  No point burning yourself out doing some insane training and then finding you hate that moveset/pokemon/ect.  Find what you like first then pimp them out.

With how easy/accessible they have made it to make perfect (5 IV) pokemon in Gen 6, there's really no reason to not invest in them.

For Fun maybe.

Especially to a newcomer, dealing with EV/IV/ect can really turn off the fun of the game quickly.  To those that are veterans to pokemon, the way may be a vast improvemtn and FUN compared to old.  But to a newcomer he could very well hate it and get turned off pokemon due to it.

Let him just do the simple things first before throwing him into a professional.  

If this were a job, you woulnd't throw the new person at everything the job entitles, you would let him get a feel fro the game first and its base compontents.  There are like 700 pokemon.  Sure not 700 will be seen in the online atmosphere, but the 100 you will see will take time to learn what its multiple types are and what those types are weak to.  

If he's up against another user and the user throws out a pokmeon, its more important to know what that pokemon is weak to and what moves it most likely has versus whether you have perfect stats or not.  Perfect stats won't help you one bit if you don't know what the opposing pokemon is weak to or leave a pokemon of yours sitting to take a super effective move.

The most important and helpful tool for online battling is knowing the pokemon's weakness and when to switch in and out.  No perfect stats help with that.  Only experience wil.  

Perfect stats let you learn the speed tiers.

Perfect stats can turn a 2HKO into a OHKO.

Perfect stats can turn a check into a counter.

Learning what's super effective against what takes a few wiki searches to solve.

If anything watch a bunch of online battles to learn the common play styles and what pokes carry what moves.

You are right that experience is key, but you can save a lot of time by making perfect pokes from the start.

What I did when I started playing competitively was copy a popular team at the time and from then I learned most stuff about the game. It also helped me a lot watching battles on Youtube. I used to watch the PokemonOnline channel. Not sure whether they still post or not, but it used to be great. It showed the battles of the highest ranked guys on the ladder.

In old gens only 3 IV's from either parent are passed down.  If holding Destiny Knot in Gen 6 that increases to 5 IV.

In old gens egg moves were only from the father. Now both mother and father can pass egg moves in Gen 6.

Before B2/W2, a parent with an everstone gave a 50% chance of offspring having the same nature.  B2/W2 and after is now 100%.

Before B2/W2, offspring's ability was as random as it was in the wild. B2/W2 and after made it 80% chance as the female parent.

In old gens catching a multiple perfect IV Legendary was nearly impossible.  In 6th Gen, Legendaries have a least 3 perfect IV's.

Gen 6 added a new attraction called the Friend Safari.  There the game generates a plot of grass with 3 different pokemon of a certain type based on friend code of your friends.  These pokemon will always have at least 2 perfect IV's.  And yes, ditto can be found there.  

In old gens all offspring are in pokeballs. In Gen 6 the offspring will be in the same ball as the mother (unless its a ditto).  

(This is comestic purely tho)

MUCH MUCH easier these days.

That's why he should use the Pokemon online simulator that lets him simply punch in the IV, EVs, abilities and held items. He can watch people play online, see which Pokemon looks cool and fits his play style, simply punch in numbers and stats he wants and test it out against others. If he likes what he sees, he tries to find those Pokemon in his game and train them there.

That's what I did.