Borderlands – Local Save Files in Co-Op on Borderlands 2

Copying the save file should be sufficient to copy your character to another computer, but I'd be suspicious that the file has some sort of ID to identify the character -- logging into one game with the same ID from two computers could be a problem.

I don't know that this ID is present, but I'd expect one to be there.

1) So, to answer your first question, IDK, but my gut says probably not possible to play the same character twice in one game.

2) No, moving the files around shouldn't cause an issue with playing online. I've used a save game editor to create characters - I play through Steam even - and didn't have any issues using the editor-created character single player or online.

Maybe you could rebuild a character to the point that you were at if you have issues?

This is the editor I've used: http://blog.gib.me/2013/04/18/borderlands-2-save-editor-revision-155/

First of all, you might want to reconsider your build. My experience with Zer0 is that his builds are highly situational, and using the wrong one in certain situations can make you feel very under-powered. I used his left (sniping) tree for the majority of playthrough 1, but after getting to the second playthrough it started feeling underwhelming-- I'm now back to it, but the other builds served me better in some situations. So, consider heading to a New-U station and re-speccing. I've found that his kunai (last skill in the center tree) can be devastating against certain enemies.

Second, you might want to grab some new guns. Guns start to decay in usefulness very quickly after playthrough 1, so if you've been using the same gun for a few levels now it's probably time to replace it. Grind a bit, or spend a few of your Golden Keys in Sanctuary. The difference will astound you.

Third, take out his surveyors first, always. They are a massive pain in the butt and trying to kill Wilhelm with them healing him is an uphill battle. But leave the other bots he spawns if they're not a huge nuisance-- you can use them for second winds.

Lastly, use your elements. Shock is THE best element overall, since it has no damage penalty against any kind of enemy and in playthrough 2 deals double damage against shields. I recommend a shock sniper for Zer0-- he'll dominate with it. Apart from that, definitely bring a high DPS corrosive gun, and slag, slag, slag. Zer0's kunai can apply slag, but if you're not using that build I'd recommend getting some slag grenades-- that way, you'll be able to slag him without switching guns.