There is no such code for that. The game can only allow you to have Pokemon up to level 100. No Pokemon over level 100 exists.
if you hack your game you can encounter a level 100 ho-oh
No because a level 60 would be too powerful and in diamond/pearl the strongest Pokemon in Cynthia has is a level 60+ garchomp. if you were allowed to catch a level 60 wild Pokemon then the game would be too easy. the same goes for all the Pokemon games, so sorry, but you cannot catch a level 60 before the elite four :(
Ha ha ha... No of course not. Gotta catch em' all. Keep striving to catch every Pokemon in your game.
You can't catch Level 100 Pokemon in any Pokemon game. The highest catching Level in Pokemon is Level 80. You need to raise your Pokemon to Level 100 or trade for a Level 100 Pokemon to get one. You can also challenge Level 100 Pokemon, but only in the organized challenges of the Pokemon games (i.e. Battle Tower, Trainer Tower).
You need to evolve Lavitar to get a Pupitar at level 30 in Pokemon Diamond. Lavitar can be found on route 207 in the game.
No the catch rate is the same in every game
You cannot catch Rayquaza in-game in Pokemon Black.
you can certainly catch Dioxies in the game Pokemon pearl
In pokemon Heartgold
For Pokemon platinum, you have to beat the game, then get an adamant orb from Pokemon diamond. It's at level 70. For Pokemon diamond, it's part of the story. For Pokemon pearl, you have to get one from diamond.
At Mt.Silver, you will find Pokemon at least level 50 to level 60. They are very tough, so try to catch one. At the peek, there is a trainer named Red. He has Pokemon for level 80 to level 88. His pikachu is the best in the game. Hope I Helped. : )