Sceptile can be both Special and Physical. Although its Physical Movepool is overlooked
In-Game its upto you weather you want to Mega Evolve Sceptile.
Competitive-wise, if you pair M-Sceptile with a Pokemon which benefits from Lightingrod can be good use. As frail as it is without the 4x weakness to Ice so M-Sceptile won't last long. So depending on how well it synergizes with the rest if team you should decide weather or not
Special
Sceptile@Life Orb/Choice Specs/Sceptilite
252 SpA/252 Spe/4HP
Overgrow
Leaf Storm
Focus Blast
Hidden Power (Ice)
Dragon Pulse
SubSeed
Sceptile@ Petaya Berry
Overgrow
252 SpaA/252 Spe/4 SpD
Timid
Hidden Power [Ice]
Giga Drain
Substitute
Leech Seed
Physical
Sceptile@Flying Gem
Jolly/Adamant
252 Atk/252 Spe/ 4 HP
Unburden
Acrobatics
X-Scissor/Dragon Claw
Earthquake
Leaf Blade