A good tutorial to start with code searching :
Introduction :
http://gamehacking.org/faqs/wiirdhacking.htm
Simple Search :
http://gamehacking.org/faqs/wiiexample1.htm
Pointer Search :
http://gamehacking.org/faqs/wiiexample2.htm
This was written for the Wii and WiiRd debugger, but if you understand how it works you can apply it to WiiU and Gecko.net
The only difference is that WiiU currently doen't have "code type".
Code type allows the use of condition (if, then, while, etc.), counters, temporary variables, etc.
for example : if address xxxxxxx > 15 then set xxxxxx to 0 (automatically reset only if value is past 15)
The pointer Search tutorial is particularly very instructive and well detailed. I recommend reading it even if it's for Wii.
The Wii has only two memory bank (80 and 90) while WiiU has 01, 10, etc.
so you can't use WiiRd to do pointer search. a WiiU pointer search program has been released! (link in the WiiU cheatcode thread)
You can apply the same method than the tutorial to generate dumps of WiiU memory and then use the wiiU pointer search program.
Currently on WiiU there's no automation. the user need to press a button to send a value to a specific address. (called "poke")
The game can still overwrite that address and your action is not preserved.
With "hooktype" on wii, you can patch existing functions (like screen buffer, controller reading data, etc.) to tell them that before exiting the function they have to jump to another function : the cheatcode handler.
this way, every time the screen buffer function is executed (60 time per seconds, like fps) the game execute the cheatcode and check the condition, edit the memory content, etc. and as it's 60 time per seconds it acts like a "fixed value" for infinite life, HP, etc.