In the mines, there are 6 modukons that must be saved, and 9 that cannot be killed (Located in the very first secret place, which includes 12(!) Mudokons). There's also one (and only one) secret place that requires Shrykull to access it, blocking another 3 Mudokons from access. In the game ender, you must rescue 2 Mudokons in order to get Shrykull (And that's the only location in the game where you must get the Shrykull), and if you're in a bad-ending condition, there are more 4 Mudokons you can not access.
300-6-9-3-2-4=276 Mudokons that can be killed. If my calculation is correct, I've appearently killed all killable mudokons!
