Luigi may have not been in Super Mario 64 for N64,Mario's Time Machine for NES/SNES,or Super Mario RPG for SNES,but neither could you control Mario in Mario Is Missing for NES/SNES or Luigi's Mansion for Nintendo Gamecube. And Mario does not hog all the action,you can beat SMB and SMW using only Luigi(if Luigi reaches Bowser's Castle first or if Mario dies). You're forgetting something:"Super Mario Bros", Mario is Mario and Luigi's last name,meaning that in SMB,Luigi was Mario's Partner,not Mario's sidecick.