Kennen & Yasuo Synergy
Kennen Top and Yasuo Mid win 52.0% of 2,109 Low Elo games together, +1.5 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.
Playing the duo
Slicing Maelstrom(R) deals area damage and Kennen's Mark of the Storm(P) stuns after three ability hits, while Last Breath(R) needs an airborne target; Kennen is follow-up control, not Yasuo's knockup setup.
How to play as Kennen
Layer Slicing Maelstrom(R) with Yasuo's tornado or Last Breath(R) so the pair's area damage and stun land while enemies are grouped; do not expect your stun alone to enable his ultimate.
How to play as Yasuo
Build Steel Tempest(Q) to its tornado before entering with Kennen, since his stun does not activate Last Breath(R). Use the airborne window to pull Kennen's area damage into the same fight.
Sources
These notes come from r/YasuoMains, checked against the champions' abilities.