These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
In the early days of the game, Mega Zor-Maxim was considered by many to be so overpowered that it led to the popularity of games using "No Mega" house rules. It's evened out a little since then, but he's still one of the most powerful monsters in the game.
On the other end of the scale, Mega Zorog has developed something of a reputation for uselessness.