Hey, Sorry I'm SO late. Better late than never I guess.
I think this episode is... alright. I don't think it's great, but I don't think it's the worst either. I at least like how it starts out with Spongebob genuinely worrying about Gary being lonely when he's at work. I also like that the setup for this episode is the classic "Gremlins" type of story, where a cute new pet turns into a vicious monster due to a trigger (being around other pets in this episode). I think the joke where the pet seller shows a picture of a real cat instead of a snail like you'd expect is funny as well. Honestly, the joke where Spongebob says "ENCHILADAS" is hilarious too. So we have shenanigans with the new pet secretly being mean to Gary and Spongebob not finding out about it, which is kind of dumb but typical. You see this type of setup in many other shows. Then the pet turns into a monster. I always found the scene where the monster is raiding the fridge funny for some reason. I think the monstrous design for Puffy Fluffy is pretty cool too, but it's also unfitting for the show. It's a little too detailed for a Spongebob character design.
Then we get to the ending scene of the episode that makes everyone hate A Pal for Gary... the scene where SpongeBob witnesses Puffy Fluffy attacking Gary in front of his own eyes.. and SpongeBob is too stupid to realize what's happening! He actually somehow thinks Gary is attacking Puffy Fluffy instead! What do I think of this? Well I guess my feelings are kind of complicated. I think the writers meant for it to be a subversion of the usual trope of the pet owner not knowing when the other pet is being mean to it. Most cartoons would have the pet owner not ever see the pet being mean, but this scene does something different by having SpongeBob see it right in front of his face and still not know. I think the writers meant for it to be funny too about SpongeBob being extremely clueless to the point of it not really making sense. I admit I think it's KIND OF funny and I respect that they tried doing something different instead of being cliche. On the other hand, I think they went a bit too far. SpongeBob isn't supposed to be this dumb or naive. And it's a little too weird for me because it really doesn't make sense. I get that's probably the joke, but it's a bit too out there and weird. They probably shouldn't change SpongeBob's character for the sake of 1 joke. So at the same time, I think this scene is pretty dumb. But it doesn't really bother me as much as most people. I like how Gary saves the day at the end though with his roping skills, tying into him watching Westerns at the start of the episode. So overall, I think this episode is alright. Not great, but not the worst for me. At least the controversial scene is only a fairly small part of the episode. The rest of it is just kind of cliche with a few funny jokes.
