I see...
As far as I am concerned, certain legendaries are exploited FOR their unique strategies or synergies - much like virtually every other Pokemon in a team. In that regard, they are no different from regular ones. Should a strategy not seem apparent to you, it's because some people prefer taking a balanced approach to cover as many opposing threats as possible, but this isn't always the case. Like I said, the term legendary is an illusion. If they dominate as much as you imply them to be, then people would use nothing but them (certainly, there are enough legendaries to fill in many teams? As a matter of fact, this very rarely happens with the banned legendaries as well - team utility takes precedence over sheer stats). The fact remains that people will mix legendaries and nonlegendaries (again, these terms don't mean anything), even the game's strongest, to produce the strategy that will benefit them the most.
Using fast hatch does not make your Pokemon illegal.
As far as I am concerned, certain legendaries are exploited FOR their unique strategies or synergies - much like virtually every other Pokemon in a team. In that regard, they are no different from regular ones. Should a strategy not seem apparent to you, it's because some people prefer taking a balanced approach to cover as many opposing threats as possible, but this isn't always the case. Like I said, the term legendary is an illusion. If they dominate as much as you imply them to be, then people would use nothing but them (certainly, there are enough legendaries to fill in many teams? As a matter of fact, this very rarely happens with the banned legendaries as well - team utility takes precedence over sheer stats). The fact remains that people will mix legendaries and nonlegendaries (again, these terms don't mean anything), even the game's strongest, to produce the strategy that will benefit them the most.
Using fast hatch does not make your Pokemon illegal.