Everyone has to give reasons why a Pokemon should be banned. For Chansey, Victini, Kyurem, and Drought, many people have given reasons, which at least lends credence to the standpoint, even if each individual person advocating for them being banned doesn't give reasons. That said, as you seem to have also noticed, I have nevertheless been demanding reasons from each person calling for a ban of one or more of those things. I certainly wouldn't say the reasons are sufficient, either, but at least they're reasons.Really? I can beat them, I never said I couldn't, but why do I have to give reasons when others don't?
But why can't you see those Pokémon banned? It's like saying: "Hey, don't ban those Pokémon, I need them for my team". Hmm? A reason for a reason, otherwise there's no point in saying something at all, right?
Your second paragraph doesn't make the slightest bit of sense. Those Pokemon all help to diversify the metagame, and that is a reason not to ban them. Unless you give a solid reason why they are breaking the metagame, no further reason is required not to ban them, because the perspective against banning them clearly outweighs the perspective in favor of banning them.
You seem to have discarded the points you were attempting to make, but I choose to make this post anyway for the sake of helping you become aware of certain other things you seem to not be aware of, which are always relevant and are things you need to be aware of. Still, though, your reasons to ban Chansey and Drought are far too insubstantial, and lack backing in evidence for exactly what they do to be broken in the current metagame. Being broken requires something far more specific than the ideas you're tossing around.