The best replacement for gameshark is action replay.

The best alternatives to gameshark are rated as following:
★★★★★  action replay
★★★★★  codebreaker
★  action replay better
★  pro action replay
★  action replay max
★  modchip
  game genie

Your alternative for gameshark is not listed? Suggest!
Speaking about gameshark, one probably shouldn't forget about emulator.

Other search terms related to gameshark and their ratings are:
★★★★★ emulator
★★★★ epsxe
★★★★ swap magic
★★★ visual boy advance
★★★ pokemon
★★★ psx emulator
★★ hd loader
★★ psx 1.13
★★ gameboid
★ pokemon emerald
★ visualboy advance
backups
modchip
You have in mind a companion for gameshark and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of gameshark in all years. Click on graph for more.
gameshark
action replay
codebreaker