queryExample.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace MCVE
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] friendlyChampionIds = {14};
            int[] enemyChampionIds = {};

            // This list includes the teams
            // 1. 22,55 vs 14
            // 2. 14    vs 15,23
            // 3. 22    vs 24
            // 4. 1     vs 22, 23

            //The linq query should return if BOTH lists of Ids match a matchup
            //but if only 1 list has Ids it should find if either team has that Id
            //I.E 
            // if the lists are {14} and {} matches 1 and 3 should return
            // if the lists are {1} and {22} match 4 should be returned
            // if the lists are {} and {14} should return match 1
            // if the lists are {22,55} and {14} match 1 should return
            // if the lists are {15,23} and {14} match 2 should be returned
       
            var listOfMatches = GetListOfMatches();

            // This query works if there's Ids in both lists, but if you have for example {14} and {} it'll return all matches
            // because it's true that list 2 matches all Ids in a team
            var fullMatchupMatches = listOfMatches
                .Where(q => q.Teams.Zip(new[]{friendlyChampionIds, enemyChampionIds}, (t, n) => n.All(nn => t.Players.Contains(n))).All()
                            ||
                            q.Teams.Reverse().Zip(new[]{friendlyChampionIds, enemyChampionIds}, (t, n) => n.All(nn => t.Players.Contains(n))).All());

            Console.WriteLine("Hello World!");
        }


        public class Match
        {
            public IList<Team> Teams { get; set; } = new List<Team>();
        }

        public class Team
        {
            public IList<Player> Players { get; set; } = new List<Player>();
        }

        public class Player
        {
            public int ChampionId { get; set; }
        }
        
        public static IList<Match> GetListOfMatches()
        {
            IList<Match> matches = new List<Match>();
            
            var matchOne = new Match();
            matchOne.Teams.Add(new Team()
            {
                Players = new List<Player>()
                {
                    new Player() {ChampionId = 22},
                    new Player() {ChampionId = 55},
                }
            });

            matchOne.Teams.Add(new Team()
            {
                Players = new List<Player>()
                {
                    new Player() {ChampionId = 14},
                }
            });

            matches.Add(matchOne);
            

            var matchTwo = new Match();
            matchTwo.Teams.Add(new Team()
            {
                Players = new List<Player>()
                {
                    new Player() {ChampionId = 14}
                }
            });

            matchTwo.Teams.Add(new Team()
            {
                Players = new List<Player>()
                {
                    new Player() {ChampionId = 15},
                    new Player() {ChampionId = 23},
                }
            });
            matches.Add(matchTwo);


            var matchThree = new Match();
            matchThree.Teams.Add(new Team()
            {
                Players = new List<Player>()
                {
                    new Player() {ChampionId = 22},
                }
            });

            matchThree.Teams.Add(new Team()
            {
                Players = new List<Player>()
                {
                    new Player() {ChampionId = 14},
                }
            });
            matches.Add(matchThree);


            var matchFour = new Match();
            matchFour.Teams.Add(new Team()
            {
                Players = new List<Player>()
                {
                    new Player() {ChampionId = 1},
                }
            });

            matchFour.Teams.Add(new Team()
            {
                Players = new List<Player>()
                {
                    new Player() {ChampionId = 22},
                    new Player() {ChampionId = 23}
                }
            });
            matches.Add(matchFour);

            return matches;

        }
    }
}