Galio vs Mel Mid Matchup
Galio Mid wins 52.5% of 1,043 Low Elo games against Mel 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
Stay offset from the minion wave and keep moving to make Mel's Q harder to land on both you and the wave. Once you have an opening, use E to close and begin charging W as you approach.
After clearing a wave, use Q and Hero's Entrance(R) to create pressure in a side lane instead of matching Mel's poke in place.
Galio can clear with Winds of War(Q) and then use Hero's Entrance(R) to join a side-lane fight, while Mel's Golden Eclipse(R) deals damage to marked enemies but does not move her across the map.
If Mel roots you as you approach with Justice Punch(E), you can keep charging Shield of Durand(W) and taunt her at close range.
How to play as Mel
Use Q when Galio has to approach the wave, and keep moving to avoid his E. If he is already closing with E and charging W, do not rely on a late root to stop his taunt.
Sources
These notes come from r/GalioMains, checked against the champions' abilities.