If PA is about pokemon just like GBA game u cant think about it similar things to balance, because:
1. It's an online game
2. Events changes everytime
3. It's way harder to get a nite and a meganium than a gyarados
So the Nite must hit harder than they do if they still with 20% roost or take back the last Dragonite.
I see a common mistake with the balancer here is, that he doesnt balance he makes a drastic change to the To-Be-Balanced Poke, like with nite roost, or ditto transform.
If they are OP the balance doesn't means to make 'em trash with a single change, you must go slowly, finding the objective way to get it balanced, ONLY THINKING AT:
1. The way you obtain it (Hard to level, easy to catch, hard to catch, easy to level, etc.)
2. The role it has (Tank, Nuker, Disabler)
3. The REAL current balance (Not one user saying "Gyara killed my nite 10 times if you don't see he playing and missing skills like a noob)
So having this things in your mind, then balance. Because every single change you are making to the pokes turns em into shit.