How to play custom build-anything map in Starcraft 2 with others?
"Unit Tester Online" is a very good unit testing map:
With this map you can easily create different unit combinations to test them. There are many options (like different terrain, enabled upgrades,...) to customize the battle you want to test.
You can play this map together with other people online, but it will not create replays.
Create a custom game and type "Unit Tester Online"
The map you're looking for should be called that, there's a lot of different versions though and it will be hard to find the best one because Battle.net 2.0 is terrible. Bookmark it when you do.