ever since they nerfed the head of f***ery decay, he's an absolute beast in hydra. he's also supposed to be able to lock down kuldath on his own. beyond that he's still a bit rubbish, but he can shore up your fire knight or faction wars team if need be.

My fireknight team is beast with Anna and a few others now faction wars yeah I'll have to do some work so that's a plus now hydra i thrown some stone skin I have laying around that has good def and hp sats what acc and speed should he have 

depends on what level you're planning to use him on. 210+ speed and 300+ accuracy should be enough on every level except nightmare (though you may want a bit more accuracy on brutal if the head of suffering is active), but you can go lower if you're only interested in the lower levels or running him in a team with a speed or tm booster.

https://docs.google.com/spreadsheets/d/1Ib1VKYIt8W3vb5IDYb1C5ain8cSxVWyUbKXJHDeRZO4/edit#gid=0 

the above link leads to a spreadsheet of the hydra's stats at all levels. it should help you to figure out what stats you'll want.

I normally run a def boost team unless it's arena  I normally have enough speed to do it by my self in the rest