Statistics involving leading Pokemon in teams are, if anything, much easier to interpret than those involving usages in teams, as there's only one lead per team (as opposed to six Pokemon in a team).

We can thus know exactly what makes a leading Pokemon overused. The definition is as follows:

**The group of overused Pokemon leads is the minimum number of Pokemon that, collectively, lead teams more often than all the other Pokemon.**

Mathematically, the group of overused Pokemon is **the minimum number of Pokemon** **whose sum of percentage usages exceeds 50%**.

Note that this definition cannot be used as the OU tier definition, as a team contains 6 Pokemon, not 1.

Doug's statistics conveniently orders lead usages in descending order. Hence, summing them cumulatively, starting from the top, until we exceed 50% guarantees that the number of leads in the list is a minimum, allowing for a very simple algorithm.

After applying this definition for this months statistics for May, here are the overused leads:

Standard Ladder:

Code:

Abomasnow
Aerodactyl
Azelf
Bronzong
Heatran
Hippowdon
Infernape
Jirachi
Metagross
Ninjask
Swampert
Tyranitar
(12 Pokemon)

Uber Ladder:

Code:

Darkrai
Deoxys-S
Groudon
Kyogre
(4 Pokemon)

UU Ladder:

Code:

Ambipom
Arcanine
Cloyster
Crobat
Electrode
Hippopotas
Moltres
Regirock
Roserade
Uxie
Yanmega
(11 Pokemon)

Suspect Ladder:

Code:

Bronzong
Deoxys-S
Jirachi
Metagross
Shaymin-S
Tyranitar
(6 Pokemon)

Here are the overused leads from January to May, for each ladder:

Code:

+----------------------------------------------------------------+
| Standard Ladder Overused Leads |
+------------+------------+------------+------------+------------+
| January | February | March | April | May |
+------------+------------+------------+------------+------------+
| Aerodactyl | Aerodactyl | Aerodactyl | Abomasnow | Abomasnow |
| Azelf | Azelf | Azelf | Aerodactyl | Aerodactyl |
| Bronzong | Bronzong | Bronzong | Azelf | Azelf |
| Gengar | Gengar | Gengar | Bronzong | Bronzong |
| Gyarados | Heatran | Heatran | Heatran | Heatran |
| Heatran | Hippowdon | Hippowdon | Hippowdon | Hippowdon |
| Hippowdon | Infernape | Infernape | Infernape | Infernape |
| Infernape | Jirachi | Jirachi | Jirachi | Jirachi |
| Jirachi | Metagross | Metagross | Metagross | Metagross |
| Metagross | Ninjask | Ninjask | Ninjask | Ninjask |
| Ninjask | Swampert | Swampert | Swampert | Swampert |
| Swampert | Tyranitar | Tyranitar | Tyranitar | Tyranitar |
| Tyranitar | | | | |
+------------+------------+------------+------------+------------+

Code:

+----------------------------------------------------------------+
| Uber Ladder Overused Leads |
+------------+------------+------------+------------+------------+
| January | February | March | April | May |
+------------+------------+------------+------------+------------+
| Darkrai | Darkrai | Darkrai | Darkrai | Darkrai |
| Deoxys-A | Deoxys-A | Deoxys-S | Deoxys-S | Deoxys-S |
| Deoxys-S | Deoxys-S | Groudon | Groudon | Groudon |
| Kyogre | Kyogre | Kyogre | Kyogre | Kyogre |
| Mewtwo | | | | |
+------------+------------+------------+------------+------------+

Code:

+----------------------------------------------------------------+
| Underused Ladder Overused Leads |
+------------+------------+------------+------------+------------+
| January | February | March | April | May |
+------------+------------+------------+------------+------------+
| Abomasnow | Abomasnow | Ambipom | Ambipom | Ambipom |
| Ambipom | Ambipom | Arcanine | Arcanine | Arcanine |
| Crobat | Arcanine | Electrode | Crobat | Cloyster |
| Electrode | Crobat | Hippopotas | Electrode | Crobat |
| Froslass | Electrode | Hitmontop | Hippopotas | Electrode |
| Mesprit | Froslass | Mesprit | Lopunny | Hippopotas |
| Roserade | Hippopotas | Nidoqueen | Moltres | Moltres |
| Staraptor | Roserade | Roserade | Nidoqueen | Regirock |
| Typhlosion | Smeargle | Smeargle | Persian | Roserade |
| Uxie | Typhlosion | Steelix | Roserade | Uxie |
| | Uxie | Swellow | Smeargle | Yanmega |
| | | Typhlosion | Steelix | |
| | | Uxie | Swellow | |
| | | | Typhlosion | |
| | | | Uxie | |
| | | | Yanmega | |
+------------+------------+------------+------------+------------+

Code:

+----------------------------------------------------------------+
| Suspect Ladder Overused Leads |
+------------+------------+------------+------------+------------+
| January | February | March | April | May |
+------------+------------+------------+------------+------------+
| Aerodactyl | Azelf | Abomasnow | Abomasnow | Bronzong |
| Azelf | Bronzong | Azelf | Azelf | Deoxys-S |
| Heatran | Infernape | Bronzong | Heatran | Jirachi |
| Infernape | Jirachi | Jirachi | Jirachi | Metagross |
| Jirachi | Metagross | Metagross | Metagross | Shaymin-S |
| Metagross | Swampert | Swampert | Roserade | Tyranitar |
| Swampert | | | | |
+------------+------------+------------+------------+------------+

(I copied Doug's formatting lol.)