I made a Splatoon weapon list before, but that was just for how much I've seen them used online. Now I'm ranking them based on how good they are. Of course this all just my opinion, but it's an opinion from one who's played the game for hundreds of hours and knows the ins and outs of all weapons, so it's probably pretty close to the actual truth. Of course if you disagree with anything feel free to let me know! Now onto the list!
*Last Updated on 10/30/15*
S-TIER
Splat Roller
Krak-On Splat Roller
Carbon Roller
Dynamo Roller
Splattershot
Tentatek Splattershot
.52 Gal
Forge Splattershot Pro *up from A*
.96 Gal Deco
Custom Jet Squelcher
Splat Charger
Splatterscope
E-Liter 3k
E-Liter 3k Scope
A-TIER
Gold Dynamo Roller *down from S*
Splattershot Pro
N-Zap '85 *down from S*
Splash-O-Matic
Neo Splash-O-Matic *down from S*
Dual Squelcher
Custom Dual Squelcher
.96 Gal
Jet Squelcher
Luna Blaster
Luna Blaster Neo *New*
Custom Range Blaster *up from B*
Kelp Splat Charger
Kelp Splatterscope
Classic Squiffer
Bamboozler 14 MK I *up from B*
Custom E-Liter 3k
Custom E-Liter 3k Scope
Slosher
Tri-Slosher
Heavy Splatling
B-TIER
Carbon Roller Deco
Splattershot Jr.
.52 Gal Deco
Blaster
Custom Blaster
Range Blaster
Rapid Blaster Pro *New*
L-3 Nozzlenose
L-3 Nozzlenose D
New Squiffer *down from A*
Mini Splatling
C-TIER
Octobrush *down from B*
H-3 Nozzlenose
H-3 Nozzlenose D *New*
Areospray MG
Rapid Blaster
Rapid Blaster Deco
D-TIER
Inkbrush
Inkbrush Nouveau *down from C*
N-Zap '89 *down from B*
Aerospray RG
Custom Splattershot Jr.
Sploosh-O-Matic
Upcoming Weapons Placement Predictions
https://nwplayer123.github.io/Splatoon/Upcoming/
Octobrush Nouveau - B
Neo Sploosh-O-Matic - C
Rapid Blaster Pro Deco - A
Bamboozler 14 MK II - S
Heavy Splatling Deco - A
Zink Mini Splatling - A
Hydra Splatling - A
Custom Hydra Splatling - A
Slosher Deco - S
Tri-Slosher Nouveau - B
Sloshing Machine - A
Sloshing Machine Neo - A
As you've seen, most weapons are good to great, with only four I'd truely say are never worth using, and none truely overpowered or completely better than the rest, so Nintendo has done a great job with weapon balance!
