The bottom right one b1 floor
Any of them you just need skill and you'll find him. And if you are having trouble it's probably because you haven't beat the 8th gym yet when you beat the 8th gym leader she will say that you don't trust your pokemon enough then go out by the portal and then use surf in the water behind you (the 8th gym is in BlackThorn city.) then keep going then you'll see a man talk to him then go in the cave there will be trainers you will need these moves to get the 8th badge though you'll need Surf and Whirl Pool. Then go in the cave battle that man thats standing there then go exactly down from him surf then go left in the water then you'll see stairs get off the surf move then battle the girl. Then after that surf on the other stair case go down then use Whirl Pool on the whirl pool then you'll go across then you will keep going down untill you see a dojo like training hut go in there. When you've gone in you'll walk up and then you will have to take a quiz of how much pokemon are too you. If you beat it the Gym leader will comer in and say that she thinks you didn't beat the quiz but after you'll get the 8th gym badge then go out of the cave professer.elm will call you saying hurry up and come down here fly down to his facilitys then he'll give you a master ball then go to cianwood island then surf too any of the whirl islands look around a bit then eventually you'll find Lugia!... Also I'm not really one of the gys who use great punctuation on computers but it makes me look my age! I normally say like how r you on here!