RE: 1st Team Critique
Hey, welcome to PokeBeach. I can tell Scyther is your favorite Pokemon, and it's really fun to build a team around a favorite Pokemon. Competitive Pokemon has a lot of tiers, with the biggest one being OU (which is what your team is currently built for). However, to encourage more success for Scyther, I'm going to propose a different solution. If you want to stick with an OU team, feel free to disregard everything I have to say.
Scyther isn't really built to play with the big league players that are Latios and Gliscor. It has a mediocre defensive typing that leaves it with several crippling weakenesses in OU aka Standard. It doesn't hit quite as hard as it needs to, and a limited movepool doesn't help out either.
However, that's OU. If you take a look in another competitive tier, specifically RU (which stands for Rarelyused), you'll fins Scyther is perfectly at home there. In terms of power level, it fits in well and it has a nice typing for performance there as well. Because of how much you want to use Scyther, I strongly encourage you to check out the RU tier.
In said RU tier, Scyther performs best with a Swords Dance set, consisting of Swords Dance, Bug Bite, Aerial Ace and Brick Break. Aerial Ace and Bug Bite are both boosted by Technician and STAB, making them quite the powerful attacks, especially after a Swords Dance. It eats one of RU's premier physical walls, Uxie, for breakfast!
As said above by Chillarmy, Scyther needs Rapid Spin support for success. RU has 3 very good ones: Cryogonal, Hitmonchan and Sandslash. Sandslash fits well in terms of defensive synergy, with Scyther resisting Sandslash's Grass-type weakness and Sandslash resisting Scyther's Rock and Electric-type weaknesses. Moltres and Charizard are two big counters to Scyther, but Slowking fits well as a teammate since it beats both of them. So right now, we have half of your team: Scyther, Sandslash and Slowking.
I'll leave it at there, because half the fun of teambuilding is to build it yourself. If you're interested in what other Pokemon are in the RU tier, check out
this link. If you'd like more help building a RU team, don't hesitate to contact me through PM, Profile Message or the chat room if you see me on. Once again, welcome to PokeBeach and good luck with your team.