DescentBB

i've used PolyTron32 to make a robot before, but i'm just wondering if these days there's a more modern robot editor (or a way to convert a model from a modern modeling package) available, since there's modern level editors like DLE-XP

Sort of. The best converter from other formats is still cob2pm, which converts from TrueSpace COB. It's about the same age as Polytron. There hasn't been any real work on maintaining or updating polymodel tools.

D2X-XL does support newer model formats - ASE and OOF (OOF is deprecated but still supported I think). Nothing else does, though, and even D2X-XL only animates POF (.POL) models.