Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Basically, this is a build for someone who manages to get against a bunch of idiots. The focus is on move speed. With Teemo's normal move ability, you will own the map, being able to get from one side to the other in no time. Also, he has a decent amount of dodge, crit, attack speed, and eventually damage. If you manage to complete the whole build, you will be able to globe trot, killing heroes as you go.
Note: While Ghost is an essential summoner spell for this concept, the second spell is optional. I chose fortify so that one might shield a turret and then come help it if needed.