Ok, it was a nice ecosystem not long ago. Oxygenating plants will help getting the water full of good bacteria, so the fish stay healthy, fast growing ones that do well where you are would be wise to add, and helophytes like iris/ yellow flags if there is any substrate/mud/muck to grow into. Helophytes can grow in mud and take oxygen out of the air to
feed into the substrate where it helps bacteria that like to change ammonia into nitrate which is plant food. They do multiply rapidly and can easily dominate a large part of the pond if not kept in check.
I've added whatever i could to my small pond, from around my area after identifying it and if it wasn't rare, but was healthy and abundant i took a bit/few to try. One in three are still in i guess. They're all good in one way or another. Flowering beautifully, or just growing rapidly. What you scoop out has sucked up nutrients algae can't have anymore.
There is no fixed recipe as far as i know of what works plant wise, it depends on where you are and who you are. If you just want to plant and walk away be carefull, if you are capable and don't mind managing and observing you can be a bit more careless in your choices.