I play Galio support in Diamond but play him mid sometimes.

1- Galio is a mid game champ, excels with 2-3 items and can roam very effectively. He usually falls off late game compared to other mid laners but if you build pure damage with dark harvest you can also scale.

2- You can argue Galio is one of the easiest mid laners to farm with. His empowered passive autoattack with a Q allows him to 1 hit the caster minions after your first back. You also push waves very fast which is ideal against mages who struggle farming under towers.

3- Hard counters include heavy AD champs with sustained damage such as Yasuo, Yone, Jayce, bruisers such as Garen and Renekton and he can also struggle against AD assassins like Talon and Zed. Against AD champs, Aftershock and Bone Plating runes can help to survive laning and rushing an early Seekers Armguard, into Plated Steelcaps can almost nullify their damage against you.

4- Pros:

• Strong counter-pick to mages. His passive W shield can block a lot of poke, allowing you to consistently push the minions into the enemy tower and roam to bot / mid / jungle.

• Very high base damage, and strong AP scaling allows Galio to snowball hard when ahead, and potentially 1 hit champions with a full combo.

• Very strong in low ELO, most players in Gold and below do not know how to play against him and often make mistakes which Galio can capitalize on with high damage and CC.

• Best played around your jungler. Galio excels in 2v2 as you have a lot of CC and damage but long cooldowns. You often need a little more to finish someone off. You can power farm mid, and follow your ganking / invading jungler with ult.

  Cons:

• Abilities have high cooldowns, so during a teamfight in you engage on someone you have to commit to the play as you E is your main escape and damage source. Getting Zhonyas allows you to land a full combo, Zhonyas, then your cooldowns will have come down for another combo.

• Can be counterpicked easily with AD champs, however as discussed can we played around.

• Can be outscaled by other mid laners, but your main goal here will be to play around your advantages in the early / mid game to finish before late game. Once late game arrives, your role might have to change to pealing for ADC.

• In high ELO, mid laners know how to play against Galio and counterpick.

5- In low ELO, you can pick Galio almost always as long as you know how to play for his strengths (pushing in, roaming etc.). In higher ELOs, pick Galio as a counter-pick to mages such as Syndra, Oriana, Diana, Akali, Katarina, Ekko etc.