I have a feeling that Sceptile was only included as a playable character in Pokken Tournament to complete the Hoenn starter trio along with Swampert's future reveal. Compared to the other Pokémon on the roster, Sceptile isn't that popular and it doesn't seem like he got in on his own merits. Then again, it seems weird that Bamco would give special treatment to the Gen 3 starters when Gen 1 is more popular...