:)

In order to get your Golbat to evolve into a Crobat, you need to do one thing. What you must do is raise Golbat's happiness level to the maximum level that it can go. Once you complete this task, your Golbat will evolve into a Crobat after you level your Pokemon up some levels. There are several different ways that you can use to make your Crobat more happy. Would you like some examples of how you can make your Crobst more happy, well then, here you are. Do not let your Pokemon faint in battle, Pokemon do not like getting knocked out so keeping them awake and in health will make them like you a lot more. If you win battles with a Pokemon, they will grow levels and get stronger, after you win a battle your Pokemon also becomes happier. Give your Pokemon vitamins and minerals such as Carbos, Zinc, Iron, Protein and other things to make their stats increase and to make them more happy. Hope this helps.

You can catch crobats in the tower where rayquaza is.

So, you want to know how to evolve a Golbat? Ok. Well, it's actually quite simple. You have to make it's happiness go all the way up. Then, all you have to do is train it a few levels. Once done so, it will evolve.

My young friend, the answer to your question is that you must raise your Golbat's happiness level to it's Max. I suggest putting it in the front and letting it win a lot of battles and let it hold a Soothe Bell. To see if you have raised it to it's max, go to the lady's house in Verdanturf city. It is the last house on the end so check on your Golbat's happiness from time-to-time. To close this monologue, you'll know when your Golbat when evolve when the lady says: " It adores you, It can't possibly love you more. I even feel happy seeing it!"

You must manage to get your crobat to evolve in a high friendship evolution. You can build the friendship a number of ways.

-Keep it as your first party Pokemon all the time
-Let it battle frequently
-Feed Pokeblocks that it likes
-Never let it faint
-Use items such as Carbos or Zinc on it

You can maximize your goldbats happiness, or go to rayquazas tower ad catch them there.

Avoid giving him any bitter things (im not sure if bitter things are in this game)