I came up with a moveset and added sweetspots to certain attack to keep his overall stranght but also make him balanced.

Luffy's Moveset

Game:Jump Superstars

Note: Due to Luffys stretching abilities, some attacks have " Sweetspots" that give added effects to the attack(s). This works similar to the tip of Marth's sword. Hits with the knuckles, palm or foot(heel, bottom, and toes for "Gum Gum Spear") cause increase damage and knockback, and in some cases meteor smashes

Smash Attacks

Basic Combo
-Jab
Range- low
Damage- 3%
Knockback- none
Speed- Medium

-2nd Jab
Range- low
Damage- 3%
Knockback- none
Speed- medium

-Gum Gum Gatling
Range- medium
Damage- 5% per hit
Sweet Spot- 7% per hit
Knockback- low
Speed- high

Side Smash
-Gum Gum Pistol
Range- medium to high
Damage- 10%-17%
Sweet Spot- 14%-22%
Knockback- medium to high
Speed- medium
Chargeable- Increasing range, damage, and Knockback

Down Smash
-Gum Gum Whip
Range- low-medium
Damage- 5%-15%
Sweet Spot- 8%-18%
Knockback- low
Speed- medium
Chargeable- Increasing damage, range and Knockback
Note: Hitting in front and then behind; if Sweet Spotted, launches opponents in the direction hit in with higher knockback

Up Smash
-Gum Gum Volcano
Range- medium
Damage- 11%
Sweet Spot- 15%
Knockback- medium
Speed- low
Note: has some end lag

Up Tilt
-Gum Gum Bell
Range- Low
Damage- 1st-8% 2nd-10%
Sweet Spot- 1st-10% 2nd 12%
Knockback- medium
Speed- high
Note: Hitting above and behind then swinging back to hit above and forward. If Sweet Spotting with the back of Luffy's head has low knockback, Sweet Spotting with Luffy's forehead(during the second hit) hooks the opponent(s) throwing them forward

Side Tilt
-Gum Gum Shotgun
Range- Medium
Damage- 8% per hit
Sweet Spot- 11% per hit
Knockback- medium
Speed- medium

Down Tilt
-Gum Gum Stamp
Range- low
Damage- 9%
Sweet Spot- 13%
Knockback- low
Speed- medium
Note: Buries opponents, meteor smashes opponents in air

Dash Attack
-Gum Gum Sickle
Range- High
Damage- 7%
Sweet Spot- 10%
Knockback- low-medium
Speed- high
Note: Sweet Spotting with Luffy's fist also increases knockback, has some end lag

Specials

Neutral Special
-2nd Gear
Note: increases speed and all attacks do 5% more damage. has a limit similar to final forms
- Has a 10sec charge before being active, can tap directional buttons to roll out but cancels charge

Side Special
-Gum Gum Bazooka
Range- medium
Damage- 14%
Sweet Spot- 18%
Knockback- high
Speed- medium

Down Special
-Gum Gum Balloon
Note: Reflects projectiles and slightly decreases melee damage, has a 3 second llimit, has some end lag

Up Special
-Gum Gum Storm
Range- high
Damage- 10%-23% if all attacks hit
Sweet Spot- 15%-28% if all attacks hit
Knockback- Medium
Speed- medium (launch)-high(attack)
Note: Luffy falls helplessly after attack, Luffy can grab ledges, has start lag

Air Attacks

Neutral Air
-Gum Gum Fireworks
Range- medium
Damage- 8% per hit
Sweet Spot- 12% per hit
Knockback- low
Speed- medium
Note: Luffy remains still while using this move, has small end lag

Forward Air
-Gum Gum Battle Axe
Range- low-medium
Damage- 14%-16%
Sweet Spot- 18%-20%
Knockback- high
Speed- medium
Note: Meteor smashes if hit by the heel or bottom of Luffy's foot. Does 2% more damage if hits the stage

Back Air
-Gum Gum Whip
Range- medium
Damage- 6%
Sweet Spot- 12%
Knockback- low-medium
Speed- high

Down Air
-Gum Gum Spear
Range- Medium
Damage- 8%
Sweet Spot- 14%
Knockback- medium
Speed- low
Note: meteor smashes if hit directly with Luffy's toes

Up Air
-Gum Gum Rocket
Range- -high
Damage- 14%
Sweet Spot- 17%
Knockback- medium
Speed- low-high
Note: aimable, Direct Contact with Luffy's forehead causes higher knockback, Luffy grabs an opponent or the stage to shoot himself in the desired direction if he fails to grab anything he suffers from end lag, grabbing an opponent guarantees a "Sweet Spot" hit, has small start lag starts slow before grabbed.