When you ask about a standard...
The connectors have been one general shape for the receiver since the death of "Futaba-G"

As far as receiver packs, that can be as subjective as any other battery pack.
Many guys use Micro Deans for their packs and as an on/off switch, reliable & efficient.
Servos today can also suck more juice than they used to.

If the pack you have has two wires & looks like it could plug into the receiver it will likely fit. just make sure the polarity & pins are lined up properly.