I have a question, since I’m not good at finding stuff like that out myself cause for me it’s always too much going on in the game, so maybe someone knows already.
In tps Claptrap took less incendiary damage and more corrosive damage than the other Vault Hunters due to him being a robot.
But what about Fl4k? Has anyone tested how Fl4k reacts to incendiary and corrosive damage and can enlighten me?
Claptrap was a unique case of wholly thought out design. He is Hyperion, so he had some loader abilities to consider when it came around. Wilhelm also had an armor as health skill. Fl4K is more like Zer0. A humanoid style robot. It would be cool, but it wouldn’t make as much sense as a skill, and as an inherent ability; it wouldn’t be the best for a sniper. You gain a guaranteed death dot (corrosive hits much longer on armor) for a couple of minor damage reductions while getting ganged by 6 Fanatics. It’s okay at best. Why aren’t you farther away so you don’t need armor, Sniper bot? (gameplay wise)
Either way, no, he has flesh like all VHs before him. It wouldn’t really matter even if he did. It gives him no real bonuses as compared to Fragtrap, which as a grenade and Explosive user, saves his ass.
Maybe I’m wrong though. Could be a great skill.
Oh, I didn’t mean that as a skill and I honestly haven’t thought about pros or cons in gameplay.
For me it would just make sense, Fl4k looks like loaderbot, has the Hyperion colours, whatever that means about the origin, and to me doesn’t seem to have flesh anywhere. For me it’s clear Fl4k is a robot, so I would logically assume a weakness to corrosion.
But I haven’t noticed any difference to the other vault hunters, so I’ve wondered from the beginning why it’s like that.
I just figured divulging would make more sense, you could test your theory yourself for sure. Not one that needs another user. Splash can self damage (Sellout has Incedenary/Corrosive too), so yeah.
But, does Iron Bear ever survive getting ganged? That is armor. It’s maybe a few shots stronger than a flesh target would be, so I’d still use that as a comparison. It’s better on paper. Much better. Armor is just health with two weaknesses (cryo and corrosive), but against normal bullets it doesn’t do wrong.
FL4K gets “human” damage modifiers because he’s wearing clothes (where Claptrap was stark naked).
I’m kidding, but that’ll satisfy me for an explanation. 
But my Claptrap wore a hat! 
My daughter is playing as FL3K and asked me this just last night.
I haven’t tested yet to know for sure, but if not, it’s most likely an oversight in game design.
Same thing happened at release of Pre-Sequel: when it initially launched Fragtrap didn’t have a weakness to Corrosive but it was added during a patch several months later.
Thematically it would make perfect sense for FL3K to have a weakness to Corrodo, being a Hyperian robot. It would also add more flavor to him as a character.
As of now I don’t have an authorative answer to give but I’ll be sure to let you know when I do.