well guys - i don't know what you're up to - but as he says - he only wants to beat a bot ( or two

) ), not win an international championship pro-game or whatsoever..
Don't make the picture that the Hydra is useless.. Especially if the map-stage is not really an open one
( "X" type maps like The Hunters ) - he only has to "survive" the Siege - and later on - just go forward step by step with expanding your creeps towards the enemy with Spores.. ( in Original - Spores + 2 groups of Hydras + Guardians is the most effective combo against Terran )..
When they start to seem desperately to you in forcing "sneak attacks" - you should be able to make 12 Guardians + 12 Devourers + 12 Lurkers + (12 + 12) Hydras at the main base or safe occupied bases.. When you've done this - just make a group - two of lings just to focus the "first fire" and "break the ice".. All of the other army - keep it together - don't fall on "provocations" - cause the "ambush" is the Terran's strongest weapon.. Especially keep an eye of the Devourers cause they just move, chase and do no harm - you know what i mean on - that really drives me crazy..
And don't forget the Detectors - since the Expansion has a medic Blind ability - "split" the overlords in groups
( 2 should be enough )
But yes - i have much problems of defending in an open stage.. ( Haven't tried the "O" type yet )
And even - if you want to break the "repeatedly sneak attack" - use the Queen to "brooling" the Tank without "Opening" the Guardians in front..
One more thing - the real strength of the Zerg - is not in "micro" and "sneaking" tactics..
The real strength is in that they "regenerate" the army faster than the opponent - so it's a massive "macro - resource" game.. If he has the economy to "renew" the army 3 or even 4 times (and has kept the Guardians alive) - he's probably the winner already..
No Terran "bot(s)" will be able to "overrenew" him if he doesn't lose the Guardians after the "neutral - terrain" battle - just bring packs of hydras and few ultras - and they will just effectively defend the rest of the "aftermath" guardians
( and never forget to bring overlord(s) - in every decisive attack )..
So people - try the above in original - and you'll be surprised how it really works ( why should it be much otherwise in the Expansion )..