As the previous user posted, a lot of those are the standard ones. I'll probably be repeating a lot of it, but I'll list the general (and most tested) competitive rules.
Banned Pokémon
Arceus, Darkrai, Deoxys (all formes), Dialga, Garchomp, Giratina (both formes), Groudon, Ho-oh, Kyogre, Latios, Lugia, Manaphy, Mew, Mewtwo, Palkia, Rayquaza, Shaymin Sky Forme, Wobbuffet, and Wynaut.
Smogon test basically everything that seems like it'd have a viable shout at being allowed in Standard OU, rather than just banning things that may seem too strong. Deoxys Speed Forme has been tested in OU before, but was eventually judged Uber. Garchomp was tested for a prolonged period of time and judged Uber. Shaymin Sky Forme went through a test early on when Platinum was released, but it was later decided to be removed for Standard play and will be re-tested at a later date. Wobbuffet has been tested slightly, but it's evident that the Shadow Tag Ability is ridiculous, hence Wynaut being currently on the ban list despite its apparent frailness. Latias and Latios were recently tested, Latias voted OU, while Latios voted Uber. Manaphy is currently being tested and by mid-April will have been decided on.
Plans for the future are likely to involve testing of Wynaut, Deoxys-D, and possibly Ho-oh. Who knows what else could happen.
I don't want to come across as elitist, especially since I'm a member of the staff on Smogon, but I just feel that the rules decided upon there are the most viable competitive rules. We spend so much time fine tuning and testing that it's obvious to see that we're doing the best thing for competitive Pokémon. While Smogon is testing and finding the best possible competitive rules, is there any other point in another forum trying to emulate this and think they can do better? I really don't think so. I'm not saying everyone should listen to Smogon, but the amount of work put in shows how comitted Smogon are. I do not have a problem with your forum having your own set of rules by any means, but I think they should rather be an alternative, not the 'suggested', so to speak. Perhaps you should emulate the Smogon rules here, but accompany it with a message like such: "It's recommened that you discuss rules with your opponent before the match, as diversity here is encouraged, so limiting certain Pokémon is never frowned upon."
Every other Legendary (and every other Pokémon for that matter) has been in Standard OU or below since, well forever, and no one has ever suggested that they should be as they've never proved too strong. Thus, they're Standard OU and should be.
Banned Items
Soul Dew
Soul Dew is currently the only banned Item as at-the-moment, Latias with Soul Dew is judged to be Uber. Latias with Soul Dew will be tested, but it's very likely to be voted Uber in that regard.
Clauses
Evasion Clause, Freeze Clause, OHKO Clause, Self-KO Clause, Sleep Clause, Species Clause
Item Clause is generally not deemed a necessary competitive rule. While at first it may seem as though it increases diversity (like Species Clause), it can also reduce it at the same time. Many Pokémon rely on the same kinds of sets to really function well, when you remove their options of items, you can also remove their viability, thus reducing diversity and making this rule seem more pointless. You can also completely remove the point of full on offensive or defensive teams with limitations of one Life Orb or one Leftovers, reducing competitiveness even more. However, in Double Battles, I feel there is more variety involved and they're often more strategic, so enforcing Item Clause here is something I approve of; though it doesn't matter much either way.
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However, I am also a fan of the Official Nintendo Tournament rules, but much prefer them in Double Battles to Single Battles, as Nintendo seem to.
Banned Pokémon
Arceus, Celebi, Darkrai, Deoxys (all formes), Dialga, Giratina (both formes), Groudon, Ho-oh, Jirachi, Kyogre, Lugia, Manaphy, Mew, Mewtwo, Palkia, Phione, Rayquaza, Rotom (all formes), Shaymin (both formes).
*Dragonite, Tyranitar
I don't understand the Rotom ban, since there are many Pokémon with slight alternate formes which are allowed. However, it's possible that the new formes of Giratina, Shaymin and Rotom do not work on Battle Revolution, which Nintendo will use for some rounds of their tournaments. Phione is again silly, but no one would use it anyway.
*Dragonite and Tyranitar are banned in the current installments of Nintendo tournaments as there is a level 50 limit, while you can only attain a level 55 version of both of them. However, you can get a level 50 Event Dragonite from Toys R Us in America, which is allowed. Also remember that Regigigas is level 1 in Platinum, while Heatran is level 1 in Platinum, so they're now allowed.
Banned Items
Nintendo must feel that this makes Latias and Latios too good, so it's banned.
Banned Moves
Judgement
Arceus is banned and not even legally available yet, so nothing can have this attack.
Clauses
I'm not fully sure which Clauses Nintendo implement, but since DS consoles and Platinum will be used for a lot of the next tournament, I'm assuming for at least this section, there will be no clauses at all. I'm unsure of what would happen in the event of a Self-KO Clause happening here, but I think this should be in play with a judge ready to determine.
However, if you're running a tournament, I think you're free to choose which Clauses you wish even if you;re using Nintendo's rules.