Other than that part where you called Magneton a liability otherwise, I thought it was a great guide. It's certainly a good starting point for beginners. Believe it or not, I intended this response to be just those 2 sentences, but I think I've come down with Pidgeot500 syndrome.
I also disagree with almost always having 4 of those Pokemon. I don't think I've ever used 4 of them on the same team as usually the other standards like Weezing and the just plain awesome UUs like Cradily can fill the gaps, and to be quite honest most of those are just plain dull to play. Either way, I'm thinking about trio/maggie/weez/regice/clops long before I'm thinking about Raikou. They're certainly the biggest threats in terms of flat out shutting a team down or sweeping it hard, but a team needs them not to be competitive.
If you were looking for more to say, I'd note that it's good to have pairs of Pokemon that cover each other's weaknesses well. Weezing/Jirachi is a great example. With reasonably standard sets(or occasionally radically unstandard if you pull it off right) they can generally switch into whatever comes in on the other. No, it's not a perfect combo(Camerupt solidly counters both, and they do run into several problem Pokemon), but it works well. Of course we also have the infamous Gyarados/Magneton which is so common that using Gyarados is considered a tip-off to using Magneton. These pairs exist in many forms, and sometimes you might stumble across some radical ones that involve extremely UU Pokemon(this is actually IMO the best way to bring UUs into standard). The reason these magic pairs work so well is that late game when you've both lost a few Pokemon they tend to anchor the team down and prevent it from being swept.
And of course the last thing to say is to always use a team you are comfortable with. Many of us have Pokemon we really just can't quite use to their full potential for a variety of reasons usually involving battling style. I know I really can't use Celebi well; it just doesn't agree with me. So for me, just because it might be theoretically best to use Celebi, I would be a fool to as I would lose it to trio every other match, and it would end up being less useful than it could be otherwise. On the same note I find myself extremely comfortable using Dugtrio so he's a good guy for me to work into my teams. At the end of building a team, you have failed if you are uncomfortable with the product. It's fine if you are new and need adjusting to it or if you want to overcome problems with using certain Pokemon, but you won't win very much if you aren't comfortable with your team.