26
level it up to level 16
Drowzee evolve into Hypno at level 26.
Lombre will evolve when you use a water stone on it, there is no other way.
A Haunter has to be traded to evolve. You have to trade it without it holding an Everstone and it will evolve into a Gengar. The Everstone will stop the evolution process.
There is no level 500 Pokemon. The highest level that a Pokemon can be is level 100.
a easier way of leveling up is below! Pokemon level 1-30 find a level 50 Pokemon Pokemon level 31-100 find a level 100 Pokemon Pokemon level 101-200 fight a level 200 Pokemon Pokemon level 201-300 fight a level 300 Pokemon and so on... WARNING YOU MUST DO THIS ON VERY EASY!!
Train your pokemon.
You can get a level one hundred Pokemon in HeartGold the same way that you can get a Pokemon of that level in other games. You have to level them up until they reach it.
You make a pokemon level X in pokemon HG or SS but a level X is a level 100 but it wont say level X for the level
Then you have a level 70 pokemon!
Level 100.
You cannot catch level 99 pokemon. You have to catch them and level them up yourself.