I attempted to write my list with a bit of an arguement to back up my fights. Also you guys left Wapol out of the fighting lists!
Franky vs Buggy - Buggy
Buggy is nimble enough to avoid Franky's long-range moves and can split apart incase Franky gets too close. Once Buggy gets behind Franky the fight will be over, regardless of Franky's own abilities. Remember Luffy won with a lot of help from Nami!
Franky vs Kuro - Either
All Franky has to do is catch Kuro once to make it a KO. However Kuro is clever and will take no time in rushing behind Franky and nailing him in the backside.
Franky vs Don Krieg - Franky
Don isn't as nimble or quick as the previous two opponents. Also his moves tend to strike forward. Don's guns would prove very uneffective, resulting in a melee standoff between the two. One's armor is over the skin, one under; thustly once Franky bashes through its game over.
Franky vs Arlong - Franky
Arlong's nose would dent if it struck Franky's Iron-Chest. And if he even attempted it, Franky would snap him in two if he came close range. Franky has an advantage in range and melee. If Arlong knocked him in the water, Arlong MIGHT win, but thats the last case possibility.
Franky vs Smoker - Smoker
Franky loses all ability to fight the Captain. However Smoker's attacks will prove mostly uneffective against Franky. In terms of a fight, there isn't one, but Smoker has the upper hand just because of his ability.
Franky vs Wapol - Wapol
In terms of ranged abilities, Wapol and Franky nearly match. Wapol would use the advantage to get close, and gladly munch Franky. Wapol + Franky fusion!
Franky vs Mr. 5 Team - Franky
Franky out-ranges Mr. 5 and laughs at his snot-bombs, while throwing Miss Valentine at the booger flinger.
Franky vs Mr. 3 Team - Mr. 3 Team
Miss Goldenweek Provides the distraction, while Mr. 3 locks Franky down and takes his time finding his weakness, eliminating him easily.
Franky vs Mr. 4 Team - Franky
Franky plucks Miss MC out of the ground and flings her at Mr.4, resulting in KO. He then uses one of his many ranged moves to take out Mr. 4 and Lassou.
Franky vs Mr. 2 Bon Clay - Franky
Franky joins in with the dancing and being silly. He then punches Bon-chan in the head before he can start doing Okama Kenpo.
Franky vs Mr. 1 Team - Franky
Franky can take both of their blows with minor damage, easily beating Miss Doublefinger with his steel fists. Mr. 1 has a body hard as steel, but Franky will just have to pummel Mr. 1 until he doesn't get up.
Franky vs Crocodile - Crocodile (Round 1)
Crocodile totally demolishes Franky, he's untouchable and immune to Franky's strong melee. Crocodile's powerful Desert moves are enough to crush Franky.
Franky vs Crocodile - Franky (Round 2)
After realizing that Crocodile is harmable when afflicted with water, Franky puts a Sprinkler system that comes out of his head. He commences to beat the living daylights out of Crocodile.
Franky vs Bellamy - Franky
PUNCH.
Franky vs Satori - Franky
Even though Mantra will give Franky a load of difficulty, none of Satori's attacks would slow Franky down enough to stop him.
Franky vs Shura - Shura
Mantra once again poses a big problem. Also Shura's ordeal of string will eventually trap Franky long enough for him to get barbequed or stabbed enough times by the fire-spear.
Franky vs Gedatsu - Franky
After Gedatsu punches Franky once, Franky retaliates, winning swiftly.
Franky vs Ohm - Franky
The Ordeal of Iron won't bother Franky as much as string. He should be able to stop Ohm's Iron-Cloud sword and then commence to smashing Ohm.
Franky vs Enel - Enel
Same technicality as the Smoker fight. Since Franky can't strike him regardless of circumstances, Enel wins without an actual fight.
Franky vs Foxy - Franky
Franky boxing vs Foxy boxing. Foxy's hits won't hurt too badly, and a few strikes from Franky's Iron fists are enough to take out anyone.
Franky vs Aokiji - Either
Depends on how Franky uses Fresh Fire and how often he can use it. Aokiji actually has no definite advantage over Franky, so this could go either way.