Playing against a bot wasn't making the tracker go up for me. I don't know if a patch was issued or something, but even if it hadn't been, it's far easier to set up a Last Man Standing match against a second controller.
On the level select screen, go into match settings by pressing
. Set the kills to 99, match time to 10 minutes, and set the quantity of explosive pies to infinite on the items tab. Then, select the Lost Island in Polynesia (as far as I know, that's the smallest level), and start the match.
After that's all done, it's a simple matter of running the second controller to the left or right depending on where you spawn, and hitting
with your main controller to throw the explosive pies. If you have a turbo controller, you can just idle the main and run the dummy. If you have a CronusMax, even better.
Lastly, be sure to hold start after every kill to expedite the kill timer. This whole process shouldn't take much longer than 30-45 minutes. Feel free to comment with any suggestions to make it faster or more efficient and I'll add them.