The best replacement for rattlesnake is cobra.

The best alternatives to rattlesnake are rated as following:
★★★★★  cobra
★★★★★  copperhead
★★★★  gopher snake
★★★  king snake
★★★  bull snake
★★  king cobra
★★  mongoose
★★  roadrunner
★★  hawk
★  black mamba
★  cnr
★  bullsnake
★  bobcat
★  cottonmouth
★  garter snake
★  eagle
★  rattlesnake
★  rattle snake
★  water moccasin
★  scorpion navy issue
  canebrake rattlesnake
  golem
  rat snake
  dominix
  rabbit
  squirrel
  dog
  garden snake
  gopher

Your alternative for rattlesnake is not listed? Suggest!
Speaking about rattlesnake, one probably shouldn't forget about black and white tail.

Other search terms related to rattlesnake and their ratings are:
★★★★★ black and white tail
★ black rattle
You have in mind a companion for rattlesnake and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of rattlesnake in all years. Click on graph for more.
rattlesnake
cobra
copperhead