To put it simply all your best/worst game weapons you have come across anything starting with PS2/Xbox/GC and going backwards is acceptable. These can be primary or secondary weapons but no power ups (by power ups I'm referring to Invincibility stars, PU's like the fire flower, etc).
Best no particular order
Plasma Grenade Halo- Nothing more satisfying than sticking an enemy with one and watching them get fragged, even better when they have no idea they've been stuck
Spread Shot Contra- Game changer, a must have to turn the odds in your favor
Plasma Gun Doom- Looked completely badass and I loved the blue plasma it unleashed
Double Barrel Shotgun Half-Life- always a favorite in tight quarter and the double shot chewed up many creatures quickly
Worst no particular order
The Paper Fan SSB- Knocks players behind you and does little damage to the player
Deku Stick Legend of Zelda Ocarina of Time- Not technically a weapon but they sucked when you did use them as one
Klobb Goldeneye- Talk about useless, like shooting a Nerf gun but less deadly
Plasma Sword Halo- Rocked in the single player but makes online matches one sided.