Is there a way to export a team from one league and import to another?
For instance, say I wanted to have a league featuring the greatest NFL teams of all time. So I go to the 1989 seasion and export San Francisco, go to 1992 and export the Cowboys, etc and then finally import them all into a new 32-team NFL league. Is there a way to do this

Kind of... you could create a league with whatever year you wanted to pull from, export the players after the league is created, then put that export into the CSV converter and filter out only the team you want. Put that team in a new sheet. Repeat for all teams and you would have a sheet with various teams from various years.

Okay if i do understand you correctly, I think you are saying what I feared - it's basically a peacemeal thing of just exporting rosters and copying/pasting/filtering as you've said...
It'd be nice to be able to export an entire team..in this game, with all the wonderful features you've given us, a team is now a LOT more than just their roster -

* Team logos, colors
* Game plans, playbooks, depth charts
* formations
* coaches

All this stuff takes a long time to do...i think it would help in a lot of instances to be able to port over all of a teams' features in one package so pls look at letting us do this in some future vers?

Not really something that's on my list. There is so much information/data/configuration on a team that just moving it to a new league likely would cause lots of bugs and issues. What we have now with the mod system and various screen imports and exports gets you most of the way there.