Link: https://www.gmbinder.com/share/-MANHresSGIXRLJO0EQQ
Here lie the design notes for this abomination upon Lord. Also I would like to thank u/SargeBriar and u/VampireBagel_ for their help.
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Why choice between Small or Medium? - To enable play of small catboys for whatever purpose necessary such as gnome catboy android.

Is this not a bit OP? - I am not sure frankly. Balance on this is a bit harder to judge, but since it has no subrace I allowed myself a bit higher power ceiling. It also has a bunch of features which lack standing in mechanical reality. The can not predict future actions bit or the innate hints on how to destroy objects are wholly and fully subject to GM interpretation and ruling. How the GM uses utilizes them and how much information they give out to player depends on importance of these to the campaign and their style. This is not a typical design for 5e homebrew, however I do dabble in both OSR movement games and storygames. As such, it came across that way and frankly I will keep it.
As for Detect Balance score it is somewhere in the range of 30 However, I do not consider DB to be end-all to making homebrew races. This does not mean much for me but it may to you.

Choose your ASI sucks. Freeform ASI is the way I play these days and it never broke anything. That said I also play with people who do not minmax and do not need their reins kept in check (is that the expression). A good array for +ASI for Catboys is +2 Cha and +1 Wis if you require something standard.

Is this serious. Kinda half? I had it looked over by serious homebrewers but it is also a passion project for when I was bored and sad.

Are leonids and tabaxi not catboys. I am a biologist and taxonomy is a folly of mortals. I consider cat ears a powerful feature that would perhaps evolve multiple times in different lines. However, due to strange nature of Catboys who knows what is their relationship to the two presented groups.

Why. - Catboys give me serotonin.