The best replacement for luigi is mario.

The best alternatives to luigi are rated as following:
★★★★★  mario
★★★  bowser
★★★  tails
★★★  waluigi
★★★  shadow
★★  donkey kong
★★  luigi
★★  tails death battle
★★  sonic
★  wario
★  mario games
★  king boo
★  mr.l
★  weegee
★  peach
★  wario and waluigi
★  wario waluigi
★  mr l
  mario rap battle
  wario & waluigi
  sonic and tails
  mario game
  mario older

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

Other search terms related to luigi and their ratings are:

★★★★★ daisy
princess peach
120 stars
120 stars on super mario galaxy
You have in mind a companion for luigi and it is not yet here? Propose!

Google Trends

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