Pokémon Gold and Silver/Tin Tower

You need a Rainbow Wing to get into the Tin Tower. In Silver version you need to wait until Pewter City to get it while in Gold you get the Rainbow Wing from the Director after Team Rocket. In Crystal you need the Clear Bell in order to get into Tin Tower, like Gold this is obtained from the Director after beating Team Rocket in Goldenrod. In Silver, you will get the Silver Wing from the Director with which you can go to the Whirl Islands to catch Lugia.

Here, you will have a chance at catching Suicune! Go save at the first bit then battle the 3 Sages for the right to go in, then save at the entrance to the tower then go in, you will see all 3 Pokémon and they will all run away (Crystal) Suicune attacks you, this is your only chance to catch it in Crystal so give it your best shot, use the Ultra balls if you have to, you can get some more of those but there is only 1 Suicune. Now you can catch the others in the grass, they are 1 of a kind but they run every time you see them, click here for advice on how to catch them. (Crystal) You will only be able to catch Ho-oh at the top when you get all three of the other legendary Pokémon.

Pokémon found

Morning	Day	Night
Suicune*	Suicune	Suicune
Ho-oh*	Ho-oh	Ho-oh

* Only one of each.

Trainers

	Sage Gaku: 1024 Noctowl (lvl. 32, 1110 EXP) Flareon (lvl. 32, 1356 EXP)
	Sage Masa: 1024 Noctowl (lvl. 32, 1110 EXP) Jolteon (lvl. 32, 1344 EXP)
	Sage Koji: 1024 Noctowl (lvl. 32, 1110 EXP) Vaporeon (lvl. 32, 1344 EXP)

Way to the roof

Now you start your new adventure, which the main goal is catch Ho-Oh. How to do that? This is not as easy as you think and you cant do that now. If you want to start this long journey, you must fulfill 2 conditions: 1. You must catch all 3 Legendary Dogs - Suicune, Entei and Raikou and have it in your team. 2. You must defeat Elite 4 and meet Eusine in Pokemon Center in Celadon City(Kanto region). If you do that all, go to the Tin Tower again and let's talk with Head Sage. After conversation staircase appear near you. Then follow the hints below:

Go up, then come to the front of that room, and climb the stairs. You'll find the beginning of the maze. There are lots of one-way jumps, and telepads.

3rd floor: Take one jump to the right, walk up, take two jumps to the left and walk around the center of the tower, take two jumps to the left, walk up, and take 5 jumps to the right, and up the stairs. (This floor pretty much gives itself)

4th floor: Walk down, do NOT jump directly below the stairs, but instead jump twice to the left, and one down. You are now standing at the center of the tower. Walk around this, and jump twice, and take the stairs up.

5th floor: Walk up, jump twice to the right, and then jump down. (There is an option to jump all the way to the right here, so pay attention). Now, jump twice to the left (one jump more to the left would send you back to the stairs) and then three times down. Walk one step to the right, and continue by jumping down twice. Now, two jumps to the right, one jump down and get up the stairs.

6th floor: Walk straight up to the center of the tower (only opportunity so far here), walk to the right, up and to the left. Now walk down, and jump down twice, then up the stairs. (pretty straightforward this floor, it really can't be done wrong).

7th floor: Walk up, and then right, past the first teleport (The red thingy on the floor), and take the two jumps to the right. Take the 2-cell wide jumps downwards (4 jumps all-in-all). Walk to the left, and take the teleporter in the bottom. From here, the path to the top is straight-forward, only one choice at any point. Walk straight down to the next teleporter, take it, and walk left-down from here to the next teleporter. Walk up, then left, to the next teleporter, around the center pillar, and up the stairs.

At the roof you find the Legendary Bird - Ho-Oh. It has Level 60 and is very strong. Its moveset is: Gust, Recover, Fire Blast and Sunny Day. The best way is use Pokemon who can put Ho-Oh sleep, because this Pokemon can restore 1/2 its Life - this is about 100 Health Points. In my opinion your team should look that:
1) 2 different type Pokemons with move which can put sleep,
2) Pokemon with False Swipe move
3) Gastly/Haunter/Gengar with Hypnosis, Dream Eater and Nightmare
4) Other Pokemons.
Try to take as many as possible HP and use then Ultra Ball. Heavy Ball shoul be good too(or even better) because the weight of Ho-Oh is over 400. You can try to use Master Ball too, but I think this isn't necessary.