Unova is full of hazards from those terrible Dragon legendaries how could that be a competitive stage
You seem to be operating on several common misconceptions. Firstly, the presence or lack of hazards does not solely determine how competitive a stage is. For example, I do not advocate the use of Mushroomy Kingdom, Golden Plains and Gaur Plain, despite that they are completely hazard free. Reversely, numerous stages with hazards have been staples of competitive play since Smash Bros. 64 (and every other Smash game). Some people don't like 'em - that is certainly their prerogative - but there is do denying that many, many, many high end, exciting and competitive matches have been played on such stages. Like it or not, they are a huge and memorable part of Smash history and will likely continue to be for years to come.
Secondly, Unova is certainly not "full of hazards." It has some significant hazards, yes, but the hazards aren't always on - in fact they are off much more time than they are on. The hazards have a very regular and predictable window - there's tons of warning for them and they have strong tells. When they do come, they are not too difficult to avoid and always affect less than half the playable area at a time. You can certainly be thrown/knocked into them, or be cornered into dealing with them, but that is part of the strategic and skill-based play and counter-play the stage offers. Yes, it can favor some characters over others, but that is the point of counter-picks. No stage is truly neutral (unless you are playing a mirror match) as there are always attributes that make a stage more favorable for one character over another. Again, this stage may be not your cup of tea, and that's good - it would be extremely boring if we all had the same likes and dislikes - but the stage is very playable at a competitive level, I assure you.