Galio vs Malzahar Mid Matchup
Galio Mid wins 48.4% of 2,302 Low Elo games against Malzahar Mid, +0.5 points vs expected, 2-patch window 26.19-26.20.
Researched on LoL patch 26.20. Tips are written to hold at any rank; stats come from Low Elo ranked games up to patch 26.20.
How to play as Galio
Use Colossal Smash(P) and Winds of War(Q) to clear Voidlings and hold the wave; look to influence side lanes with Hero's Entrance(R) instead of repeatedly trying to force Malzahar out.
Colossal Smash(P) deals area damage, letting Galio clear several of Malzahar's Voidlings(W) with one empowered attack.
Galio's magic resistance and durable kit make him difficult for Malzahar to push out or kill alone, while Malzahar can punish Galio if he roams by pushing the wave.
How to play as Malzahar
Do not spend the lane forcing a solo kill on Galio. Keep the wave moving, and when Hero's Entrance(R) takes him to a side fight, push for the wave or plates he leaves behind.
Sources
These notes come from r/MalzaharMains, checked against the champions' abilities.