As Terran
Make:
Siege Tank
Widow Mine
LiberatorHydras melt when they must walk through zones.
Open in the counter tool with Hydralisk tagged ->As Protoss
Make:
Colossus
Disruptor
High TemplarAll reliable Protoss answers are splash or range based.
Open in the counter tool with Hydralisk tagged ->As Zerg
Make:
Lurker
Baneling
InfestorLurker zones and Fungal punish Hydra clumps.
Open in the counter tool with Hydralisk tagged ->
Zergling
Roach
Ravager
Queen
Mutalisk
Corruptor
Overlord
Overseer