Good, Neutral, Bad Ending is with the gauge only, so I assume you got those. And the rest I copy in, because writing it out every time can be tiresome. xD
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Secret Slave Slut Ending is very easy to achieve. Basically full "Evil" gauge and you get a choice after Digitamamon struggle-snuggled Gomamon. Huh, thought unlocking the punk outfit was also needed, but seemingly not as I just checked. So, that makes it even easier. I mean, the other one is a lot harder in comparison.
And here a short explanation I copied in from when I explained the Secret Lover Slut Ending to someone else:
"You need the three special scenes. Bodyjob first with Clawjob cumming outside twice and Blowjob cumming outside once. Second and third scene will require other things, like to always have saved him or tried to save him from Digimon. Not to mention a large blue good bar. The third scene requires you to not go through the third Firewall after having found it. If all other requirements are met the third scene triggers and after having all three you will get the ending you want. ^^"