How & where to catch the following pokemon:- 1)Jirachi 2)Deoxys 3)..

1)A PokemonColosseum bonus disc but you can only transfer it 2
Ruby/saphire so trade it 2 Emerald.
2)ActionReplay or NintendoEvent then go 2 Mistic island.
3)Beat the P/League then go 2 the weather institute.
4)Beat the P/League then go 2 the weather institute.
5)Beat the P/League Then Have a Wailord First And a Relicanth last in your
Party then go 2 Pacifidlog and surf untill you reach a small diveSpot Go Under
Then Go down untill you reach some dots then dive out the water and go up untill
U can't then use dig.Go through the hole then go up till you can't And read the
Brail(just press a then a again).Then it should say a rumble occured from far
Away.

1) You need an AR/GS or Nintendo Event

2) Same as above

3) Once you have defeated the Pokemon league, go to the Weather Institute and one of the guys in there (not sure which one) will say it has been really sunny or something like a drought happening in a certain route. If you go to that route it will be really sunny, like what happens on Pokemon Ruby when you go and find him in the underwater cave. There will be a cave hidden in the route somewhere, Groudon is inside that cave.

4)Same as the above except the Weather Institute guy will say it has been heavily raining in a certain route. Go to that route and dive down underwater and an underwater cave will be there, Kyogre is in that cave.

5)Hard to explain but I know for a fact that there is a hint on how to unlock their seals in "User Submitted Cheats" named as:
Regice Seal
Regirock Seal
Registeel Seal

And how to unlock their three doors do this (I found this on the SuperCheats Website but not sure if in User Subbmitted Hint or Cheats):
Things you need: TM 28 Dig, Relicanth and Wailord.

Fly to Pacifidlog and surf to the left. You will see water currents to the left of screen, go down to the very bottom current and ride that, you will land on a platform and battle a fisherman (that's if you haven't already battled him). After this is done ride the current in between the two rocks. When you land you will see trainers walking back and forth. Walk to the left and then walk straight down and ride on the bottom water current. You will end up behind two swimmers, swim straight ahead and ride that current. When you land ride the bottom current again. When you land this time go straight forward and ride the current. When you land surf into the miidle of the water where no currents are and dive down in the dark patch. Swim up until you see an entrance, go inside and walk straight up the middle of the cave, and press A on the wall, then use Dig and walk straight through. Then keep walking straight up and put a Wailord in the first slot in your party and a Relicanth in the Last slot in your party and press A on the wall. Now you have unlocked the Three Regi's doors.

Jeez, my fingers hope I helped.

You have to migrate them from other games.