I didn't see any good tally mark LoRAs for Pony, so... here's one.

Using the body tallies one their own, e.g. 'tally on chest' with parentheses seems to work fairly well. You'll get some bleed over to other parts of the body, but it mostly works. 'Tally on wall' is inconsistent, but does work if you have other supporting elements.

Turn up the weight on your location tag to increase the number of tally marks, and/or use the base 'tally marks' tag to increase the distribution across the body. You will probably get some body writing as well, especially if you use the base 'tally marks' tag.