Why isn't Netflix bringing the older episodes of Pokemon online?

Or are they still to come

It is unknown.

Because they don't have the license to do it. It is not yet clear whether they will still get it.

Why isn't Netflix bringing the older episodes of Pokemon online?

Netflix is only allowed to broadcast what you bought the licenses for. They probably won't have done that for the old episodes

Netflix has to get the licenses from the rights holders, which of course also cost money. If it doesn't pay off because the demand isn't that great, then you won't spend unnecessary money on it.

On the other hand, the rights holder can simply say no to an extension or to the distribution of a license in general. Or you have issued licenses to another provider and want / may be with several providers.