Introduction
In DPP and olders gen there are no team preview which is basically mean you will have a 'lead match up' so you have to choose the right one for your team and god know isn't an easy task.
I will give you a list with various types of leads like suicide leads,bulky leads with their advantages and their disadvantages.
Suicide leads : Most of them are just used to setup hazard as much they can (for spikes/t-spike users) with sleep move,taunt which prevent other slowers lead to setup their hazard and explosion which remove one big threat or wall in the start of the game.
Azelf :It's one of the most versatile leads, because you can choose from like Focus Sash / Choice Scarf or Band / Dual Screener / Colbur berry. Its high speed allows it to set up SR almost always, while fast Taunt can be useful sometimes. The other moves depend on its set.
Aerodactyl : Aero is a really fast pokemon, and having both SR + Taunt make it a reliable Suicide Lead. It's usually Sashed, while it can be Power Herb + Sky Attack sometimes to KO non-sash Machamp.
Froslass : Froslass has a good niche in being a fast lead that has access to Taunt, Spikes and Destiny Bond. Other moves such as Icy Wind and Shadow ball can be used in the last slot.
Infernape : Ape has access to Fake Out + Stealth Rock + Endeavor in addition to a high speed and a strong attack stat
Roserade : Roserade is pretty good as a lead, you will almost always put something to sleep, then set your Toxic Spikes in the field. Other than that, Leaf Storm hits hard and HP Fire provides coverage(HP Ground allow you to hit Heatran).
Mamoswine : Mamo is a decent lead, It gets Stealth Rock and the Endeavor + Ice Shard Combo. In addition to that, It is strong and has an acceptable speed.
Smeargle :The fact that Smeargle learn every move makes it a decent lead. Usually you spore something, then you set up your Entry Hazards. U-Turn in the last slot enables you to scout and pressure your opponent with a switch-in if he taunts.
SR Leads + berry : With their natural bulk/typing they can set their stealth rock and attack the opposing lead regardless weakness thanks to their resist berry.
Jirachi -Jirachi has an insane movepool, It's usually Occa with SR / Psychic / Grass Knot or Tbolt / HP Ground. But some people use a defensive Leftovers version with SR / Body Slam or Twave / Iron Head / Wish and that's absolutely fine.
Metagross - Same typing as jirachi and acces to explosion/SR and good bulk which means its really good lead.
Lum berry/Occa berry or custap berry (leaving eq ada from scarf flygon and boom with the custap)
Heatran - SR + 3 attack (Fire Blast/Earth Power/Explosion-Hidden power-WoW)
Shuca Heatran lives EQ from adamant Scarf Flygon, Passho beats LO Starmie and Swampert if it carries HP Grass. Focus Sash is used sometimes.
Empoleon - SR + 3 attack (Grass Knot/H Pump/Aqua Jet/Ice Beam) make him good lead
Focus sash or sometimes chople berry.
Celebi - SR + 3 attack (leaf storm/hp fire/earth power) with the occa berry for tran/ape.
Azelf - See Suicide Lead Azelf.
Bronzong - Same typing as gross with same moveset (not bullet punch sadly).
Occa berry or leftovers if you are using heatproof over levitate.
Bulky leads : They are just setting their hazard and taunting/phazing other lead,they can back early game thanks to their bulks.
Hippowdon - Same as swampert but without the water typing but with recovery other than leftiez and countering well zapdos/dnite mixed with the spedef set.
More used on defensive team (semi stall/stall)
Swampert - Good typing,SR and Roar/Protect for explosion users,water/ground typing allow him to beat lead like infernape/zapdos without hp grass which is very helpfull.
Nidoqueen - SR/T-Spike and Roar made him good lead for defensives teams.
Gliscor - Acces to stealth rock/taunt/u-turn,natural bulk allow him to check threat like sd lucario in late game.
Skarmory - Cool lead since you have acces to taunt/spikes/whirlwind/roar which allow you to beat other defensives lead (not gliscor) but you are sadly beaten by common lead like azelf/zapdos/dnite and he being trapped by magnezone.
Forretress - Don't really like him as lead,honestly you are not going to use a defensive entry hazard setup/remover who is beaten by like all leads in the game right ? also he is trapped by magnezone.
Uxie - Bulky lead,acces to Stealth Rock/T-Wave/U-turn.
Blissey - Acces to stealth rock but not really other usefull move which make him good lead and he is also beaten by machamp/dnite/azelf ect.Its definitively lead who is bad in the metagame.
In DPP and olders gen there are no team preview which is basically mean you will have a 'lead match up' so you have to choose the right one for your team and god know isn't an easy task.
I will give you a list with various types of leads like suicide leads,bulky leads with their advantages and their disadvantages.
Suicide leads : Most of them are just used to setup hazard as much they can (for spikes/t-spike users) with sleep move,taunt which prevent other slowers lead to setup their hazard and explosion which remove one big threat or wall in the start of the game.
Azelf :It's one of the most versatile leads, because you can choose from like Focus Sash / Choice Scarf or Band / Dual Screener / Colbur berry. Its high speed allows it to set up SR almost always, while fast Taunt can be useful sometimes. The other moves depend on its set.
Aerodactyl : Aero is a really fast pokemon, and having both SR + Taunt make it a reliable Suicide Lead. It's usually Sashed, while it can be Power Herb + Sky Attack sometimes to KO non-sash Machamp.
Froslass : Froslass has a good niche in being a fast lead that has access to Taunt, Spikes and Destiny Bond. Other moves such as Icy Wind and Shadow ball can be used in the last slot.
Infernape : Ape has access to Fake Out + Stealth Rock + Endeavor in addition to a high speed and a strong attack stat
Roserade : Roserade is pretty good as a lead, you will almost always put something to sleep, then set your Toxic Spikes in the field. Other than that, Leaf Storm hits hard and HP Fire provides coverage(HP Ground allow you to hit Heatran).
Mamoswine : Mamo is a decent lead, It gets Stealth Rock and the Endeavor + Ice Shard Combo. In addition to that, It is strong and has an acceptable speed.
Smeargle :The fact that Smeargle learn every move makes it a decent lead. Usually you spore something, then you set up your Entry Hazards. U-Turn in the last slot enables you to scout and pressure your opponent with a switch-in if he taunts.
SR Leads + berry : With their natural bulk/typing they can set their stealth rock and attack the opposing lead regardless weakness thanks to their resist berry.
Jirachi -Jirachi has an insane movepool, It's usually Occa with SR / Psychic / Grass Knot or Tbolt / HP Ground. But some people use a defensive Leftovers version with SR / Body Slam or Twave / Iron Head / Wish and that's absolutely fine.
Metagross - Same typing as jirachi and acces to explosion/SR and good bulk which means its really good lead.
Lum berry/Occa berry or custap berry (leaving eq ada from scarf flygon and boom with the custap)
Heatran - SR + 3 attack (Fire Blast/Earth Power/Explosion-Hidden power-WoW)
Shuca Heatran lives EQ from adamant Scarf Flygon, Passho beats LO Starmie and Swampert if it carries HP Grass. Focus Sash is used sometimes.
Empoleon - SR + 3 attack (Grass Knot/H Pump/Aqua Jet/Ice Beam) make him good lead
Focus sash or sometimes chople berry.
Celebi - SR + 3 attack (leaf storm/hp fire/earth power) with the occa berry for tran/ape.
Azelf - See Suicide Lead Azelf.
Bronzong - Same typing as gross with same moveset (not bullet punch sadly).
Occa berry or leftovers if you are using heatproof over levitate.
Bulky leads : They are just setting their hazard and taunting/phazing other lead,they can back early game thanks to their bulks.
Hippowdon - Same as swampert but without the water typing but with recovery other than leftiez and countering well zapdos/dnite mixed with the spedef set.
More used on defensive team (semi stall/stall)
Swampert - Good typing,SR and Roar/Protect for explosion users,water/ground typing allow him to beat lead like infernape/zapdos without hp grass which is very helpfull.
Nidoqueen - SR/T-Spike and Roar made him good lead for defensives teams.
Gliscor - Acces to stealth rock/taunt/u-turn,natural bulk allow him to check threat like sd lucario in late game.
Skarmory - Cool lead since you have acces to taunt/spikes/whirlwind/roar which allow you to beat other defensives lead (not gliscor) but you are sadly beaten by common lead like azelf/zapdos/dnite and he being trapped by magnezone.
Forretress - Don't really like him as lead,honestly you are not going to use a defensive entry hazard setup/remover who is beaten by like all leads in the game right ? also he is trapped by magnezone.
Uxie - Bulky lead,acces to Stealth Rock/T-Wave/U-turn.
Blissey - Acces to stealth rock but not really other usefull move which make him good lead and he is also beaten by machamp/dnite/azelf ect.Its definitively lead who is bad in the metagame.
