As Terran
Make:
Marine
Reaper
HellionA wall, one mobile unit, and calm worker pulls remove most Reaper value.
Open in the counter tool with Reaper tagged ->As Protoss
Make:
Adept
StalkerShield BatteryDeny cliff vision and keep the first gateway unit near probes.
Open in the counter tool with Reaper tagged ->As Zerg
Make:
Queen
ZerglingSpine CrawlerPull weak drones early and use the first Queens to end the poke.
Open in the counter tool with Reaper tagged ->
Marauder
Hellbat
Widow Mine
Cyclone
Siege Tank
Thor
Viking
Medivac