good cheats for pokemon crystal that you dont need a cheat devise to do?all the onse ive come across you need a stupid devise to do so if theres any good ones worth doing without a devise can you let me know?

Most of the good cheats/hints are talked about in Pokemon hints/tricks thread at https://www.vizzed.com/vizzedboard/thread.php?id=5548
It depends on what you mean by good cheats.
Like Yellow, most of the glitches in gold/silver were fixed in Crystal because they damage your game.

But heres one that might work, but it might not work either, its up to you to test it.
Also a note: Use this code at your own risk. It may corrupt your save data and Vizzed can not recover your save game.

Go to a PC, and save. Attach the item you want to duplicate to the Pokemon you want to clone. Deposit it into the PC. Change boxes. When the screen is saying "Saving the game..." Turn off your GB. Turn it back on. You should have the deposited Pokemon in the PC, and a clone of it in your lineup. The item will either be on both monsters, or in your Backpack. Note: while doing this code, DO NOT withdraw any Pokemon. When the GB is turned back on, you'll find that the withdrawn Pokemon has been deleted.

Honestly though I dont see the point in all these cheats, every item and pokemon in the game except the legendarys are easy enough to get multiples of, it just takes a little time.