Teleport

4 min (240 second) cool down if you Teleport to a tower

5 min (300 second) cool down if you Telepoort to anything else

Flash

5 min (300 second) cool down

If at all possible call out the timings when any enemy champion uses one of these abilities.

Look at the game clock and mark the time. When you have a moment type in chat Vayne Flash 12 (which would mean that at 7 minutes into the game Vayne flashed and it is going to be down until 12 minutes into the game.)

The math on that:

Game Time = 7 min
Flash cool down = 5 min

Vayne's Flash will be up again at 7 + 5 = 12 min Game Time.

This is information that you and your team can utilize.

No flash on the their ADC? Your jungler should come by for a gank.

The enemy team used three flashes in the last team fight? Either look to pick-off the champions that Flashed or try and start another team fight before they get their flashes back as this will limit their mobility and escape or engage potential by quite a bit.

The enemy top laner just teleported back to lane? Now might be a good time to go take Dragon as you know that their Top laner is going to have to walk all the way down from top lane to assist their team if they decide to contest Dragon.

Above and Beyond

You are probably going to have to use a 3rd part site like Curse Voice to tell for sure if someone is running Summoner's Insight which is a utility mastery that can reduce the cool down of summoner spells by up to 10%.

If you know for sure they are running it shave off 24 or 30 seconds for Teleport or 30 seconds for Flash.