Like Singed, Teemo and Kassadin
Im a dominion noob, teach me forum masters

Delete Teemo.

There is no solution for Kass besides chain-CC or the Kass player's brain being functionally broken. Sorry : \

For Singed, build armor pen and don't chase through his poison.

But, the real solution to backcapping is not to sit in the bush above windmill. If your team is camping the forest, when that Teemo/Singed starts running toward your mid you can roll over him and love every second of it. Jungle control is the best counter to backcapping. But that requires teamwork and if you are in solo Q that isn't happening...

But the payoff is huge. If you catch them in the forest backcapping you have numbers advantage in the next team fight.

There are a number of ways, but it really depends on the situation and what you have available to you.

1. Global ult and another speedy champions of your own.
2. Have a kiter with a good escape (or 2-3 normal guys) hang out in the jungle between mid and top for faster response time to protect.
3. Have one of your initiator build Boots of Mobility.
4. But if all else fails or if there is no team work. All you can really do is gank bot to draw the top groups attention and make them come to the bot. It creates an opportunity for your team to get top while 1-3 people on their team come down.

Hang around the speed shrine.

buswhacks and set up ganks

Communicate to your team to start camping the speed shrines and keep an eye on the back capper. Use pings to get your team to move with you (I know at low elo you often get these kids that berate you for "talking too much" or pinging, just calmly explain and stay positive).

Poor communication on the enemy team can lead you to 4v3 stomps allowing you to split push bot or mid and sending 2 more to roam.

If all of this proves too difficult, if you locked in a decently mobile champion you can chase and harass the back capper. For kassadin, your team is just going to have to land CC and shut him down. For teemo pick up a grez or sweeper and harass him off the point, look to gank. For singed you can just harass and force him to run off somewhere else.

if they have someone dedicated to back capping have your whole team hang out in the bushes near the speed boost, or 4v3 them and take their mid

By strict adherence to the first rule of Dominion.

Don't Chase.

Actually, if the person is dedicated to backcapping, say a Zilean with Mobo Boots and Zeals, then you absolutely have to follow him. The match essentially turns into a 4v4.

Best counter to back cappers are floaters and global ults (pantheon maybe)
Don't have ur team camping the top windmill brush for prolonged time (They assume that the enemy will only and always go for the top point)
~Always have floaters, especially with teemo around shrooming ur jungle 24/7
Teemo needs to risk getting caught in brush if he wants to shroom key areas, so camp mid brushes in the jungles
~Never bunch up if you find out that someone is just backcapping you all day, have 1 split up and camp ur speed shrine or something unless all 5 enemies are seen in the map
~If someone just back caps all game, you might as well ask a teammate or urself to stalk that backcapper the whole game making the game 4 v 4~