We should work on a defensive threat list. I'm sorry, but regarding Celebi and Spiritomb as "non-threatening" is just asking for trouble. A lot of new players will prepare teams to deal with the OFFENSIVE threat list, and get 6-0d by a sub calm mind Celebi or getting annihalated by a well played Spiritomb. Pokemon like Suicine, Celebi, Spiritomb, Dusknoir, Porygon2, Hippowdon and Blissey I think belongs in this category.
Just because something isn't going to "sweep" your team per se, it is still capable of dealing massive damage. If people aren't taught how to deal with these super dangerous defensive pokes, they'll run into problems very quickly.
Oh, and for the record, Porygon-Z is not better than P2 in EVERY WAY. Porygon2 has 515 base stats, and Porygon-Z has 535... not too much of a boost for an evolution IMO. Porygon2 tanks, Porygon-Z sweeps. You can't really say Porygon-Z is better if they don't even do the same thing.
So, here's some DEFENSIVE THREATS and why I think they deserve a mention:
Porygon2
COMMON SETS:
Thunderbolt, Ice Beam, Toxic/Thunderwave, Recover @ Leftovers
Thunderbolt, Ice Beam, Recycle, Recover/Rest @ Lum Berry
Ice Beam/Tri Attack/Toxic/Thunderwave, Substitute, Conversion2, Recover @ Leftovers (yes, I have seen this, it's so annoying)
USAGE: Porygon2 is mainly used for it's ability, Trace. It's stats aren't awful, but they're not good either. It has 85/90/95 defenses. Thankfully, it easily reaches 266 Satk so it can OHKO most of the bigger threats in the game. It can come in fearlessly on Heatran, Vapoeron, Jolteon, Arcanine, DDmence, Gyarados, Flygon, Claydol, etc because it's ability either softens the attack or renders him immune. He can stop a lot of deadly sweepers, and can even recover off the damage afterward. If only his attacks packed a bigger punch. Oh well.
POSITIVES: It's bulky, it gets Recover, and Boltbeam. An excellent tank that can switch into a variety of pokemon. Counters Gyarados 100% of the time.
NEGATIVES: It's slow as molasses, and it's normal type. Lack of resistances and STAB hinders it somewhat.
Celebi
COMMON SETS:
Psychic, Calm Mind, Leech Seed, Substitute @ Leftovers
Substitute, Calm Mind/Swords Dance, Recover, Baton Pass @ Leftovers
Recover, Grass Knot, Leech Seed, Perish Song @ Leftovers
Leaf Storm, HP Fire, Psychic/Shadow Ball, Rest @ Choice Specs
USAGE:
Celebi is an old Advance standard, constantly being debated uber. Game Freak slapped Celebi around a bit this generation with U-Turn and Pursuit, ensuring it stays in OU for now. It's a scary world for Celebi nowadays, however, with 100/100/100 defenses, Recover, and Leech Seed, Celebi won't go down in one hit unless you are using STABed U-Turn or Bug Buzz. It's that tough. Whatever you do, NEVER EVER send Blissey into this. Blissey is it's food. It can use 101 HP subs, and Calm Mind up while you feed it pink gooey juices thanks to Leech Seed. As a matter of fact, Celebi gains more than 101 HP each turn in this situation. Never allow this to happen, too many new players try this and lose. Once Celebi sets up, IE has a sub and some boosts or leech seed, you must crack down on it. Pummel it constantly until it's forced to give up. A smart player won't waste all sixteen subs on you, so it will leave eventually. If it tries to baton pass boosts, or if things look hopeless phaze it out. Don't use Swampert for this because it may use a grass move on you. If you are careful it can be beaten. Blissey beats specs verisons all the time.
POSITIVES: Best Grass Type in the game award goes to Celebi. It has handy resistances to Ground, Water, and Fighting. A huge variety of recovery options and Natural Cure ensure it won't die on you.
NEGATIVES: Seven weaknesses. Count them; SEVEN. You'll hear "It's super effective!" on Celebi over half the time. Thankfully, after one or two Calm Minds, Ice Beams won't break your sub without STAB. Pursuit sucks.
Spiritomb
COMMON SETS:
Will O Wisp, Pain Split, Sucker Punch, Pursuit @ Leftovers
Taunt, Nasty Plot, Shadow Ball, HP Fighting @ Leftovers
Taunt, Pain Split, Shadow Ball, Hypnosis @ Leftovers
USAGE: Spiritomb is really the only usable pokemon that has no weaknesses. (sorry Sableye :| ) It has the ability Pressure too; compound this with the fact that it takes three or more hits to take down, and it's one annoying legion of 108 ghosts. Three immunities is nice too. Fighting and Psychic immunities means poor Alakazam and Azelf are stuck using crappy moves like Grass Knot on you. It's even immune to Explosion (ha ha again azlef) and Rapid Spin. Taunt is a wonderful move in general, and stops Blissey and Cress from trying to do stuff against you. It's one of the best CM Cress counters, because it has to use a crappy Ice Beam against you (eight times maximum, too) and cannot heal thanks to Taunt. Anyways, Spiritomb makes a wonderful addition to any team, because it can switch into so many attacks, saving your pokemon's butts time and time again. Once more, rapid spin blocker :P
POSITIVES: Fairly bulky with 50/108/108 defenses. Max out HP always though. No weaknesses makes it sturdier than it looks. Counter Gengar, Alakazam, Azelf, and scarf/specs PZ.
NEGATIVES: Crappy HP, poor type coverage, unreliable recovery in Pain Split (it's blocked by sub for crying out loud) and once again, CRAPPY HP!!
I'll do more later... but we really need a defensive threat list. Stall teams are super popular nowadays, and people need to know how to counter them.