I realize I'm rather new here, but I'd like to contribute a submission for this. This team builder thread is a really great idea and can help out when others and I build new teams for RU.
Tangrowth @ Leftovers
Trait: Regenerator
EVs: 252 HP / 252 Def / 4 SpA
Nature: Bold (+Def, -Atk)
-Sleep Powder
-Giga Drain
-HP Fire
-Leech Seed
Role: Bulky Attacker / Tank
What It Does: Thanks to an excellent Base 125 Defense, a great Trait in Regenerator, and access to Giga Drain and Leech Seed, Tangrowth makes for an excellent tank. Tangrowth is public enemy #1 of Water types, bulky or not, including the likes of Kabutops, Omastar, and Slowking and Lanturn to some extent. Sleep Powder is very effective in stopping any sweeper in its path of destruction despite its shaky accuracy, and Leech Seed provides yet another source of recovery for Tangrowth if Regenerator and Leftovers aren't enough.
Also, one should mention that Tangrowth's 100/115/50 attacking stats are respectable bar its pitiful Speed, and so Tangrowth can abuse Giga Drain and HP Fire to a good extent and recover from a hard hit pretty easily. Although rather weak on the special side, Tangrowth is awesome at checking many of the common physical sweepers seen in RU.
Good Teammates: Slowking deserves a special mention to form the Regenerator combo with Tangrowth, allowing for fast recovery for both Pokemon. As a bonus, Tangrowth deals with Electric, Grass, and physical Dark type attacks aimed at Slowking, and Slowking takes the Fire type attacks directed at Tangrowth. To top it off, Audino can be the third member of the Regenerator combo to take Bug type attacks from Escavalier and Galvantula (actually, any Pokemon capable of taking Bug type attacks can be helpful to Tangrowth's success. Moltres gets a special mention here, forming a FWG core).
Specially defensive walls such as Lanturn or Cryogonal can also be helpful to make up for Tangrowth's abysmal SpD stat. Physical attackers like Entei and Aggron can take care of special walls such as Clefable and Roselia. Since Tangrowth has a tough time hitting Sap Sipper users such as Bouffalant and Sawsbuck (especially the former), Gallade gets a special mention in being able to take them down.
What Counters It: Anything that can take advantage of Tangrowth's weaker SpD stat are the main counters here. Moltres makes quick work of Tangrowth, and Entei can still demolish Tangrowth with Flare Blitz and cripple Tangrowth's common partner, Slowking, with Toxic. Accelgor can come in on anything, even HP Fire, and threaten Tangowth with Bug Buzz. Sap Sipper users appreciate the Attack boost, especially Pokemon like Bouffalant and Sawsbuck, and hit back with a powerful Head Charge / Double-Edge / Megahorn. Finally, special walls like Clefable and Roselia get in Tangrowth's way and often threaten Tangrowth with Toxic (and even with Tangrowth's excellent recovery, Toxic is one of its main enemies).
Any Additional Info: If you choose to run Power Whip, run Relaxed so you don't lower Tangrowth's Attack. For optional moves, HP Rock is helpful to get rid of Moltres, Earthquake deals with Drapion and Aggron, and Substitute gets a special mention because Tangrowth is able to make 101 HP Substitutes (however because of Tangrowth's Speed it is often hard to accomplish).
Tangrowth @ Leftovers
Trait: Regenerator
EVs: 252 HP / 252 Def / 4 SpA
Nature: Bold (+Def, -Atk)
-Sleep Powder
-Giga Drain
-HP Fire
-Leech Seed
Role: Bulky Attacker / Tank
What It Does: Thanks to an excellent Base 125 Defense, a great Trait in Regenerator, and access to Giga Drain and Leech Seed, Tangrowth makes for an excellent tank. Tangrowth is public enemy #1 of Water types, bulky or not, including the likes of Kabutops, Omastar, and Slowking and Lanturn to some extent. Sleep Powder is very effective in stopping any sweeper in its path of destruction despite its shaky accuracy, and Leech Seed provides yet another source of recovery for Tangrowth if Regenerator and Leftovers aren't enough.
Also, one should mention that Tangrowth's 100/115/50 attacking stats are respectable bar its pitiful Speed, and so Tangrowth can abuse Giga Drain and HP Fire to a good extent and recover from a hard hit pretty easily. Although rather weak on the special side, Tangrowth is awesome at checking many of the common physical sweepers seen in RU.
Good Teammates: Slowking deserves a special mention to form the Regenerator combo with Tangrowth, allowing for fast recovery for both Pokemon. As a bonus, Tangrowth deals with Electric, Grass, and physical Dark type attacks aimed at Slowking, and Slowking takes the Fire type attacks directed at Tangrowth. To top it off, Audino can be the third member of the Regenerator combo to take Bug type attacks from Escavalier and Galvantula (actually, any Pokemon capable of taking Bug type attacks can be helpful to Tangrowth's success. Moltres gets a special mention here, forming a FWG core).
Specially defensive walls such as Lanturn or Cryogonal can also be helpful to make up for Tangrowth's abysmal SpD stat. Physical attackers like Entei and Aggron can take care of special walls such as Clefable and Roselia. Since Tangrowth has a tough time hitting Sap Sipper users such as Bouffalant and Sawsbuck (especially the former), Gallade gets a special mention in being able to take them down.
What Counters It: Anything that can take advantage of Tangrowth's weaker SpD stat are the main counters here. Moltres makes quick work of Tangrowth, and Entei can still demolish Tangrowth with Flare Blitz and cripple Tangrowth's common partner, Slowking, with Toxic. Accelgor can come in on anything, even HP Fire, and threaten Tangowth with Bug Buzz. Sap Sipper users appreciate the Attack boost, especially Pokemon like Bouffalant and Sawsbuck, and hit back with a powerful Head Charge / Double-Edge / Megahorn. Finally, special walls like Clefable and Roselia get in Tangrowth's way and often threaten Tangrowth with Toxic (and even with Tangrowth's excellent recovery, Toxic is one of its main enemies).
Any Additional Info: If you choose to run Power Whip, run Relaxed so you don't lower Tangrowth's Attack. For optional moves, HP Rock is helpful to get rid of Moltres, Earthquake deals with Drapion and Aggron, and Substitute gets a special mention because Tangrowth is able to make 101 HP Substitutes (however because of Tangrowth's Speed it is often hard to accomplish).