Train travel Basel to Warsaw

You'd be better off flying direct from Basel and Warsaw. That only takes 2 hours in the air.

I train ride would take a minimum of 15 hours and require you to change trains 2-5 times depending on the time.

My suggestion is to take a few days and make stops along the way, or take a night train. There are many options, several scenic routes and a few high speed lines a long the way.

Another option is as mentioned to fly. But while there are direct flights from Basel to Warsaw, they are not that frequent (twice a week) and you'll find more options if you look at flights from Frankfurt or Zürich.

If you think you might like to make some stops along the way, you can take a look at rail routes by searching the Deutsche Bahn website, using Basel Bad as the origin and Warsaw as the destination. Choose one of the routings and click on Show details, then on Further information. That will show you all the stops the trains make.

Other departures may take different routes.

I'm not sure that Deutsche Bahn will show all the options, but it shows quite a few.

There is nothing particularly scenic between Basel and Warsaw. Take a train to Zurich airport, and both LOT and Swiss have several direct fights every day. There is at least one direct train from Basel to Zurich airport every hour and it takes less than 1 1/2 hours, and there are many trains per hour with a connection at Zurich main station.

For more info on trains, visit the Man in Seat 61.

You can also just do a blind google search of Train Basel Warsaw and see what pops up.

If you take the night train it is 1 change at Berlin. Depart Basel SBB at 9.13pm on train NJ 409 and arrive Berlin Hbf at 0720. Depart Berlin Hbf at 0951 and arrive at Warsaw at 1554.
There are later trains at 1351, 1552 and 1752, if you wanted to spend the morning in Berlin.
Although I love the night trains I might be inclined to spend the day in Basel, then take the one change train next day at 0706 from Basel SBB arriving at Berlin (Platform 7) at 1432. This is an ICE High Speed service. Then depart Berlin (Platform 11) at 1552, arriving at Warsaw at 2145.- simply not to miss the scenery on the way to Berlin. But I miss out on Berlin unless I take an overnight stop there, which of course I can.
If I wanted the Berlin stopover I could take an 0906 from Basel to Berlin as well- although the 0906 connects to Warsaw you don't get there until almost midnight.
Of course DB show all the trains. That is something which they do very well indeed, right across Europe.
Basel SBB is the main station in Basel, and the one most travellers would use. The ICE to Berlin also stops at Basel Bad if that is your preference.