Legendary Pokemon

I don't really feel like writing about anything significant today, so I suppose I'll do another Pokemon Post. This one details all the "Legendary" Pokemon from Generation 1 through 4.

Generation 1

The Legendary Birds
Articuno - Articuno is the first Legendary that you're able to catch in Red/Blue/Yellow and Fire Red/Leaf Green. It's a dual type - Flying and Ice. You'll want to catch it if you want to have an easier time defeating the Elite Four, especially if you're like me and only level up a Kadabra the entire game up until the Elite Four and then find yourself royally screwed. Articuno is found on the bottom floor of the Seafoam Island caves and has no signature move. (However, as one of the only five Ice Pokemon in Generation 1, it could learn Blizzard, Ice Beam, and Sheer Cold naturally.)
Zapdos - Zapdos was the second of the Legendary Birds that you could catch. It was also a dual type - Flying and Electric. Zapdos was never my favorite Legendary, I thought Articuno and Moltres were better. It has no signature move, and can be caught at the end of the hidden Power Plant dungeon.
Moltres - Moltres was the fire type of the other two. Again, not much to say here. I preferred Articuno to Moltres and Zapdos. Moltres could be found on Victory Road in Red/Blue/Yellow, and on One Island in Fire Red/Leaf Green. It has no signature move.
Mewtwo - The only (and I do mean only) reason to get a Fire Red or Leaf Green cartridge if you own Diamond and Pearl, as all other legendaries can be gotten from events. Mewtwo was a psychic powerhouse, with amazing stats in both Special Attack and Speed, making it rival only one other Pokemon in the game - Alakazam. It could be caught at the end of Cerulean Cave, which would only open up in R/B/Y if you had defeated the Elite Four, and in FR/LG if you completed a really annoying sidequest after defeating the Elite Four. Mewtwo's signature move is Aura Sphere, but it can be learned by 5 other Pokemon which will all be covered.
Mew - The original unobtainable Pokemon. Mew could not be obtained anywhere other than a Nintendo event in R/B/Y, and would not appear naturally in any game until Emerald, and even then, you needed some kind of event triggered to give you the item to have a chance to go and catch Mew. Mew's claims to fame are base stats of 100 in every area, as well as the ability to learn any TM or HM. Like Mewtwo, it learns Aura Sphere at level 100. In Diamond/Pearl, Mew can only be obtained by transferring a Mew from R/S/E or FR/LG.

Generation 2
Raikou, Entei, and Suicine - These guys were exactly the same as Articuno, Zapdos, and Moltres, except they were legendary Beasts instead of Birds. None of them had any signature moves, and were really, really annoying to catch in G/S/C. Once you found them, they would run somewhere in the wild, and you would have to track them to specific area. The only way to get these annoyances on D/P is through having them from an event, or catching them in FR/LG. One was activated in the wild after you completed the National Pokedex. The one that was released depended upon the starter you chose at the beginning of the game. Oh, and they have no signature moves.
Ho-Oh - Ho-Oh was the Gold Uber Legendary. Ho-Oh was caught in a temple in Gold, and by an event in R/S/E that allowed you to go to Naval Island. You could also get one from an event or from beating Pokemon Colosseum. Like Moltres, it was a Fire/Flying type. The difference is that Ho-Oh has better base stats than Moltres, as well as a signature move - Sacred Fire at level 85.
Lugia - Lugia was the Silver Uber Legendary. Lugia was caught basically in the same place as Ho-Oh, but in a different game. It was a Psychic/Flying Pokemon, and could be gotten in the same way as Ho-Oh. It's signature move is Aeroblast.
Celebi - Woo! Widely regarded as the hardest Pokemon to legitimately obtain in all the Pokemon games. There has never been a way to naturally catch Celebi in the United States. Celebi could be caught in one of two ways: 1) Through the Japanese Pokemon Colosseum Bonus Disk, and 2) Through the Pokemon Journey Across America 10th Anniversary Tour, where you would have a chance of getting a 10 ANIV Celebi. Celebi is the Mew of Generation 2, and has the stats to reflect it. It's a Psychic/Grass type, who, oddly enough, does not have a signature move.

Generation 3
Regirock, Regice, Registeel - In an attempt to bring back the triad of legendaries, they chose the three Regis, all of whom are relatively useless. And by relatively, I mean completely. Whereas in Generation 1, you would use the legendary Birds in battle, by this point, there were so many much better Pokemon that it just didn't make sense to use the Regis. They had no signature moves and could be caught by doing a really annoying sidequest.
Groudon - Groudon was the Legendary unique to Ruby. It is a Fire/Ground type and could be caught towards the end of the game, before the Elite Four. It has no signature moves, but it can learn both Eruption and Fissure naturally.
Kyogre - Same as Groudon, but for Sapphire. It's a pure Water-type. Kyogre is one of two Pokemon to learn Water Spout (the other is Wailmer/Wailord).
Latios/Latias - The Latis were the Legendary Beasts of Gen 3. They were activated, and then you had to wander around a lot until you met one. They're Dragon/Psychic types, no real signature moves.
Deoxys - This dude was cool. Depending on which game you got him in, he would have a different form. Normal, Attack, Defense, and Speed. Each of these forms had a different level-up moveset. You could catch Deoxys by getting an event in Emerald or by going to events.
Jirachi - This little Pokemon has more events than any other Pokemon (besides possibly Pikachu). That's good, because it's the only way you can get him (the easiest way was probably through the bonus disc given with Pokemon Colosseum in the US.). It's signature move is Doom Desire!

Generation 4
Dialga/Palkia - The Diamond/Pearl signature monsters. You can get them on the top of a tower somewhere. Dialga's signature move is Roar of Time, while Palkia's is Spacial Rend. They are Dragon/Steel and Dragon/Water, respectively.
Cresselia - The Legendary Dog of Gen 4. Psychic type, no real signature move.
Uxie, Mesprit, Azelf - They chose a psychic trio for this game. It made no sense, they're even more useless than the Regis.
Heatran - Steel/Fire Type. Found after beating the game. It's signature move is Magma Storm.
Giratina - This thing actually looks pretty awesome. Found after beating the game. Signature move is Aura Sphere.
Regigigas - King of the Regis and almost as useless. You needed to have all three Regis in your party to even battle him. It learns Giga Impact at level 100.
Manaphy - Yay! The only way you could get this Water type was by beating Pokemon Ranger and transferring the egg over. It was pretty cool, actually. Its signature move is Heart Swap.
Darkrai - This guy is so awesome, but you can only obtain it through a Japanese event currently. Its signature move is Dark Void, and there is also an event Darkrai that has both Roar of Time and Spacial Rend.
Shaymin and Arcaeus - Not legitimately obtainable yet.