I agree with what you are saying about them having "arch enemies" that can shut down their flow but Teebo can prevent that toon (usually two for about 5 turns) from ever taking a turn.
Teebo goes stealth to start the encounter granting 100 percent turn meter to everyone else. Chirpa can mass attack to remove turn meter from one toon (also granting speed up). Teebo can then attack a second toon removing all turn meter.
Because of speed up and Elder granting additional turn meter, Teebo can remove TM at least one more time and often a second time. By then his stealth is refreshed, which restarts the TM plus speed-up train.
They seem to be very effective as long as the correct enemies are controlled while you whittle away at their health.