This isn't bad. It has a great monster selection for an 80s Godzilla game, yeah Mogura and Gezora being in the game is a little odd considering the game's release and there were plenty of monsters to add instead of those two (like Megalon), Toho monsters are interchangeable like that. The levels could've been smaller and also could've had some more objectives instead of just fighting monsters, but the areas you go through are short so it could be worse. The fights themselves are great too, even if they're cheap sometimes. What do you think of Monster of Monsters?
It's a fun game, have a lot of nostalgia for it. Being able to control Godzilla with its rather big sprite and fighting all the classic monsters is definitely cool.