Um, Toxic doesn't use anywhere near the energy capacity of Poision energy. At least 1.5 Sludge Bombs would though. Also, energy is energy, it get transformed into different types when they use those types of attacks, so there is no such thing as regular energy, it makes it sound like they pokemon has many different pools of energy. Just say, they are breathing heavier or whatever and then say, the dont have much Electric-type left. etc.
Also, although it's possible, it's not common for an ICe Beam to freeze the entire pool over, just like its possible, not common that a Flamethrower will totally remove all of the ice. Be careful when reffing excatly to what the battlers wanted. Make an RNG to determine how far the pool is ocovered with ice, since the attack was directed more at the Dratini, etc etc