243a0200_ne_Arena_Strategy___Blue_is_Me__Advantages
[Name] Hydralisk [Disadvantages] Needs lots of upgrades to be effective. Beetles, Devil dogs, Warp Zealots and Tanklings do well against it. [Advantages] 
Hydralisks are great versus armored units such as goliaths, stalkers, beetles and immortals. They can be hard to stop with upgraded health / damage, and broodlings ability.
Starcraft 2: Marine Arena Strategy | Blue is Me
Advantages