Okay, several people trying to counter what I say. This is going to make the thread worse, so I probably won't reply after this.
Obviously you need to explain why and stop throwing around random statements as if they're somehow common knowledge.
Because they are? Anyone with a good knowledge of Pokemon should be able to answer this question.
Shaymin can make 101 HP Substitutes, has Seed Flare, Air Slash, incredible speed, all perfectly abused.
Togekiss doesn't have any of that except Air Slash and it's speed is too low.
Jirachi doesn't have any of that except the Substitutes and it can't use the Substitutes as well as Shaymin-S.
No one uses Serene Grace Blissey.
Dunsparce is extremely slow and weak.
Absol and Honchkrow have Super Luck which in my opinion is not as good as Serene Grace (I can't comment on these well since I have never used them).
Banning moves would be outrageous to the other pokemon.
Oh yeah, very funny. Why don't you go and look in the analyses? You'll see that there are pokemon who have sets that abuse luck. Eg. The Evasion set for Cacturne. Why is this allowed on the analysis, if in fact, the metagame is ONLY based on skill?
You said "encourage", not based on. The metagame is clearly a little based on luck, with CH moves and all.
Define "gamebreaking". From what I've seen, the metagame hasn't been "broken" in any way by Shaymin-S's presence, and I've been testing the thing from the very beginning of Platinum. It may be another threat to look out for, and I agree that it is a good pokemon, I'm just not convinced that it's uber. I mean, look at the other suspects. They don't have nearly as many disadvantages as Skymin compared to their advantages. They don't find it obscenely hard to come in again if they get forced out. They don't find it difficult to kill a pokemon if they don't have luck on their side (or defend against strong hits for defense-oriented suspects), etc, etc.
I said as gamebreaking, by the way, I didn't say gamebreaking.
To be perfectly honest, I've noticed that Shaymin-S is a matter of personal opinion. Some people find it easy to deal with, some people find it hard to deal with. While I find it's dependence on luck hard to deal with, you seem to find it easy. I actually found Deoxys-S quite easy to deal with!
I also got quite high on the ladder with Seed Flare and Air Slash, you may not have had the same story.
They don't find it obscenely hard to come in again if they get forced out.
I disagree here. Stealth Rock is preventable (albeit common) and ground, water, fighting moves are really common. Prediction is also useful. It can also heal itself with Leech Seed. I've found it quite easy to get in.