Here’s a challenge for the “is it / is it not” argument. It’s a grimer. Literally just a regular grimer. Except it’s delusional and thinks it’s Twilight Sparkle. So, monster pony or not? :P
Celly tried numerous times to just up and attack the sphinx instead of playing her riddle game. Sphinxy’s response each time was more or less “I like you! You’re silly!” :P