Well....let's say there are three scenarios there.<br/><br/>Scenario 1) They have nothing on them except their "basic gear." That is, Batman has stuff like his Batclaw and his Batarangs and his goo...thing...and smoke pellets and whatnot, and Doom has the various magical and technological trinkets he usually carries around. The armour is non-negotiable since it's...y'know...literally melted onto his skin.<br/><br/>Scenario 2) They have what they could carry with them realistically speaking. So, Batman has what could fit in his Batjet and Doom has what he could bring in his...magic...flying...chair thing.<br/><br/>Scenario 3) Whatever they could realistically prepare and transport given the prep time. Of course, in my opinion, that kind of favours Doom since you would assume that Batman wouldn't know the terrain ahead of time (since Doom is too smart to allow Batman of all people to have knowledge of where the fight is going to happen in the first place more than maybe an hour ahead of time) but for this hypothetical, we'll say that they have access to the same knowledge regarding terrain and location and whatnot for their weeks prep time.