No no monsieur! There are two fairly salient points against this point The first is this Intelligence in this context is better translated as Sapience, which a dog does not have. It may indeed be sentient (possessing the ability to perceive and react), but without sapience it cannot be rightly said to be intelligent, except in much the same way as a computer may be considered so. The second is this Given the authors "anti-cookie cutter" mentality and his demonstrated sense of humor, combined with the strange phrasings of the target as "Non-Highly Intelligent" and "Biological Being" means that the author is not likely to use a "beast" creature or any other standard CN / Anime animal companion trope. As such it's far more reasonable that the author is planning to use some atypical target like a human, which is most likely to be someone he knows who is a little dense, So basically go through the characters we've met allies and enemies and consider which one would provide the most amusement to the reader based on the author's sense of humor. Since Slimes/Monsters/Demons/Ghosts/Spirits/Animals are fairly common as companions in most novels, we have to consider the groups normally exempt from such status. Also really, who didn't want ash to smack misty with a pokeball back in the original series.