A dedicated lead is essentially a Pokemon that is geared towards being your lead most, if not all, of the time. With the advent of team preview, dedicated leads such as suicide leads are no longer common. (The most common form of suicide lead was a fast Pokemon with an entry hazard move, Focus Sash, and maybe Taunt. The idea was to guarantee the set-up of entry hazards while attempting to prevent your opponent from doing so.)
Do you think they are a waste of space on a team? Do you have any ideas on what they could be used for, if they're worth a team slot?