Transmission fill / drain plug question

[Corbusa]

I went to drain my trans fluid today, and noticed someone had used channel locks or something on the fill plug, . it also looks like they might have tried the wrong tool on the inside of the plug. So my questions are what is the correct size of the fill and drain tools? and are the plugs available to buy? I'm sure there has got to be a few different transmissions that use the same plugs. ( ps i didnt remove the plugs , I am waiting to try and use the correct allen socket. thanks