These are wonderful cards at selling something important
As for the two big decks, I guess you could ban Emrakul, the Promised End from GB Delirium, but I'm not even sure how much that would matter
Since many Hydras also generate +1/+1 counters, it couldnt hurt to also work some +1/+1 counter synergies into the deck like Hardened Scales and Conclave Mentor
It requires a touch of political finesse to assure it comes back your way a great bargain would be trading it to the player whos falling behind but it adds interest to the board state and often sparks interesting deals that you wouldn't get otherwise
If your reanimation target isnt essentially paying for itself the moment it touches the battlefield, then it should either be individually hard to kill, feature some extremely potent reward for keeping it around, or both
Scry increases the chances you have the situational cards when you need them and not when you don't