I've seen people at our local/area tournaments in wheelchairs, walkers or walking with a cane given a preffered seat. We just route their opponent to their set table. As mentioned earlier, this happens too at US Nationals. Just happy to help anyone that loves the game to play the game.
At leage we try very hard to be patient with all players. Many just never seem to get the game. They don't improve much in their play, but we league leaders work with them, give them pointers, sometimes pair up the better players to play a game against them giving helpful pointers. I don't know if these players are mentally challenged or just bad at card games, but they keep returning and we're happy to have them. I think Pokemon draws a wide range of players. We too lose too many kids once they hit junior high.