To capture Lugia, you need to go to the Whirlpool Islands near Cianwood Island. But first you need HM06 and the Silver Wing by defeating Team Rocket in the city before BlackThorn, and also defeating Team Rocket in the Radio Tower. Then after you get those items,go to Whirlpool Islands. Use Whirlpool to get past the whirlpools, then work your way through the maze. A Lugia (Lv.40) should be at the end.
To get Celebi, you have to catch Suicune, Entei, and Raikou, and then trade in Articuno, Zapdos, and Moltres. Then, go to Viridian City in Kanto. Outside of the Battle Station there should be a woman. Talk to her, and she'll give you a GS Ball. Go back to Ilex Forest, and get to the shrine. Put the ball in the shrine, and Celebi (level 5) will come out of it.
