I have no idea if this film is part of the DC:EU, the DC:AU, or anything else, so I'll just say right off the top that there are elements of the set-up and wider lore here that I'm not going to critique or try to work out, because I think you just have to skip over that stuff and ignore it before this film makes any sense.
With that said, I was expecting this to be a kid-targeted mess of silly set pieces, slapstick and toilet humour, and very little else. What I found was a surprisingly self-aware and often quite fun story with an unusual moral centre, focusing on the pain of growing apart from close friends (with an undertone of how to handle a remarriage in a family), and how that can be a positive step for everyone involved.
I mean, let's be clear: the plot isn't winning any awards. But it knows when to poke fun at itself and when to take itself seriously, which is more than can be said for a lot of "adult" superhero movies. Plus, they had so much fun with the guinea pig's powers, and that whole "all of the Justice League ends up with a pet at the end" bit was hilariously heart-warming 😂
Plus, I was not expecting Kevin Hart's character to either be interesting or have a surprising level of depth, but that whole backstory of a dog that saved his family's young child, but in doing so inadvertently nipped her arm, and ended up in the pound, actually got me a little bit 😅 Ditto his whole "once we're free of this place, we can go live in the farm up state" thing turning out just to be him knowing that the other animals needed some glimmer of hope, and that's all he felt he could do for them. Not all heroes wear capes 😭
The result was a solid, fun romp. Nothing spectacularly original, but good enough throughout, and with no glaring issues. It is another DC film that constantly uses Marvel references and jokes (at their own expense, often), which is a little tiring, but I'll forgive that for grumpy Batman and Aquaman playing with a water-form guineapig at the end 😂