Battle tips
Ducks: After flying, they will charge. Stun them with Punches. With proper timing and walking towards them, you can stun-lock Ducks.
Hamsters: They are annoying when charging, but after they burrow they start to bite. When biting, use Jabs to take them out. Jabs out-range bites, so they usually can't hit you.
Giraffes: Stay airborne and use Punches or Jabs around the head. Try to stay "inside" of them - keeping your character between the Giraffe's head and tail.
Hydra: You need to stay airborne. They will roar before doing the head-sweep attack, so watch out. For 5x Hydras, quick Jabs will deal a ton of damage. In the 10x battle, you will be spending most of your time getting dealt damage and less time attacking, so use Punches instead. Stay airborne with the double-jump, stay "inside" as many Hydras as possible, and don't get pushed into a corner. 10x Hydras is really a roll of the dice; sometimes you crush them, sometimes they just hammer you to oblivion.