As always, the fastest way to win matches is doing this in Deathmatch, no Fog of War, and the AFTER PARTY Skull.
Don't do this with Strongholds! The enemy just spams units and it's annoying...
After Party Skull gives you a free tank and infantry every time you lose a base.
Pick Deathmatch, 9999 resources, an Easy enemy AI, any map, and the Skull AFTER PARTY.
Any other helpful Skulls, and NO Fog of War.
When the match starts, quickly build on all the build points around the map, then on the closer build points to the enemy start destroying and rebuilding as soon as you can. Switch between bases to save a few seconds. Do this until your population is maxed, then select all units and target the enemy base!
If you need any reinforcements, just destroy some more bases.
Repeat 3 times for the achievement...