CustomGame.IsHeroChosen(int slot);
public bool IsHeroChosen(
    int slot

Slot to check.
Type: int

Checks if targetted player has chosen a hero.

The code below will switch everyone who hasn't chosen a hero to the opposite team.

using System;
using System.Collections.Generic;
using CustomGameOW;


static void Main(string[] args)
    CustomGame cg = new CustomGame();

    List<int> slots = cg.playerslot;

    // Check each slot filled
    for (int i = 0; i < slots.Length; i++)
        // Check if player chose a hero
        if (cg.IsHeroChosen(slots[i]) == false) 
            // If not, switch them to the opposite team.