How to download/use cheats?

I notice on some of my friend's R4s, they seem ot have cheats. How do I use/ download these?

try this website,http://cheats.gbatemp.net/those cheats are the most updated ones, try to get yourself informed about which file you need, i recommend using the usrcheat.dat or the cheat.dat
you have to put one of these files in the _system_ folder not both, because they will stand in each others way and you wont get cheats at all.the R4 most likely wont show every cheat there is for every game...
that's because the R4 has a manufacture failure, which means it cannot load files bigger than a certain amount of KB or MB, you can avoid this failure by doing some things, but firstly put one of those files in the _system_ folder and we'll see then ;)

Use usrcheat.dat from the link above and place it in your _system_ (or equivalent) folder. For issues on the cheats not appearing, read the Common Issues https://www.romulation.org/forum/index.php?topic=1462.0

check my tutorial ;)