The game is FF9, the opponent Ragtime Mouth. It asks quiz questions which the player has to answer to win the fight. Note the quiz card he's holding:



Now, the other face of the quiz card, which is probably near-impossible to get a close look of in-game:



Texture:

It reads: "Pop Quiz! FF10's theme is GUTS! True or false?"

Several monster textures also have little doodles hidden in the alpha channel of unmapped regions but no specific message.

(crossposted from Selectbutton)