Three Steps Ahead vs "Final Showdown"
Three Steps ahead says "create a token of creature or artifact you control". It does not say, "create a token of creature or artifact card you control".
Final Showdown says "all creatures lose all abilities until end of turn". It does not say, "all abilities do not function for all creatures currently in play but they still have those abilities and all other abilities work fine in
all other instances until end of turn--just not the creatures in play right now".
When you cast Final Showdown to remove all abilities of all creatures, copying that creature should produce a creature without any abilities.
While untested in full, is it that casting Final Showdown impacts "all creatures" (graveyard, exile, entering into play, copies, tokens) until end of turn as the text states, or only the creatures which are in play at that moment? Expected behavior would be the text of the card.
Basic idea:
https://youtu.be/sDc_6cqS6TM?si=qIGxkYglYvdjF4rB

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Rezzahan#77802 commented
Since Final Showdown's first mode changes characteristics (creatures losing abilities), those creatures are locked in at the time the effect is created. It does not carry over to creatures entering the battlefield later. Like the second mode, the effect of which is generated after the first mode is done. And copy effects are applied in layer 1 when determining the characteristcs of objects, the only thing earlier is the actual base card or set of characteristics a token is created with. Ability losing happens in layer 6, so quite a while later. This essentially means, that copy effects copy the base characteristics. The only exceptions to that are other copy effects and face down status (so copying a Clone copying something else, gives you a copy of that something else).
611.2c If a continuous effect generated by the resolution of a spell or ability modifies the
characteristics or changes the controller of any objects, the set of objects it affects is determined
when that continuous effect begins. After that point, the set won’t change. [...] "So Final Showdown doesn't have to specify that it affects only the creatures currently in play. The rules already do that.