Running euchre for 18
For 18 players you will need 4 tables, 4 euchre decks (9 up to ace), and 5 sheets of paper for the score cards (four to a page). With 16 or 20 players nobody would sit out.
Give each guest a number as they arrive. Each round, find your number: the pair before the "v" sits North and South, the pair after sits East and West, so partners face each other. Many parties play 8 hands a round, then everyone writes their team's points on their card and moves when the host calls time.
Each score card lists that player's table, partner and opponents for every round. Want names on them, a different number of rounds or a fresh shuffle? Open this chart in the planner.