Overall, this team looks pretty good. Let me give some advice on what you could do to make it better.
Gliscor - Perfect.
Breloom - Now, since you're running Spore, and since you're using a Focus Sash, I would run Drain Punch over Mach Punch to regenerate your health, in case your opponent switches out to something that can OHKO you.
Greninja - I have a Greninja on my team as well, and it's exactly the same, except I have it hold a Life Orb instead of an Expert Belt, since there are still 320 Pokémon that you can't be super effective on.
Rotom-W - Apparently, you EV trained its HP and you're running Pain Split. You could just change the EVs, but if I were you I'd make Rotom-W your lead. Just give it a Choice Scarf and switch Pain Split for Trick, since it traps your foe into using a status move. Considering how neither Gliscor nor any other Pokémon on your team is a very good lead, I'd highly recommend this.
Mega Mawile - You may want to switch Iron Head for Brick Break, since Steel moves aren't very viable competitively and Fighting moves provide more coverage. Keep it if you want the dual STAB.
Haxorus - Looks great, except... is that a Lum Berry? I understand your concerns about burns and paralysis, but Haxorus would do much better with a Weakness Policy or a Life Orb.
So there's my opinion on what you could do. If you have any questions/suggestions, please leave a comment and I'll do my best to get back to you.
Hope I helped!
