I made another thread a week or 2 ago on this page, you can try searching it or googling it to see if anything comes up. A lot of interesting responses there.
But wow, I didn't know I have been using hexadecimal this whole time, but like you, I thought about using A as 15 and F as 10, and thus I name my 15/14/15 Machamp a ABA while my 13/9/15 Machamp is a C9A.
I begin it with a # and a Chinese character for the prefix of the typing of attacks (it saves you character space but it helps I am a Chinese speaker, use whatever works for you)
For example if I have a Gyarados with Dragon attacks I still treat it as a dragon rather than water/flying. My 87 Gyarados with 14/10/15 and DT/OR would be named thus:
龍 BFA DTOR