Being kind is a luxury in Smash, it can't possibly please everyone and it can't be "fair" to them all. For instance, we don't have equal representation of all six generations for instance, and in fact, we nearly had Melee not represent Generation 2 at all character-wise. Not everything is going to be fair, and it shouldn't be used to push a character, the character should sell itself.
Regardless, they can still play favorites no matter what. Even in the base series, members of a certain starter group tend to get more love then the others in promotion and the like, with Charizard being the big example of that, and that does mean some get overlooked. Sceptile is a case of the latter, it doesn't have much going for it as it's outshone by both of its compatriots and in general isn't that notable of a Pokémon, especially not to the extent of those like Charizard, Mewtwo and Pikachu. It's only saving grace is the fan theory surrounding its typing, and that's not the best way to sell the character. So regardless of fairness, it can be ignored.