Udyr is by far the most versatile champion in the game. His ability to perform almost any task that the team needs him for is why he is also very hard to play. You have to know how to build him correctly to face the team that you need. This guide is for the new players who are not comfortable yet building him for each situation that they face.

THIS GUIDE IS TO LEARN TO PLAY UDYR, NOT FOR HIGHLY RANKED GAMES. SITUATIONAL BUILDS ARE ALWAYS BETTER

Pros:
-Great midgame, you put out dps very quickly after you get that zeal
-Much easier to learn Udyr without having to figure out what to build on the fly
-Can initiate and tank for a team, or let another tank initiate and put out massive dps and CC

Cons:
-Not a strong early game
-Blue buff dependent early game
-If used incorrectly, the 5 second cooldown to revert to a stance can be deadly. Especially against a Katarina in her ultimate

While I personally have not been able to fill out my runebook with this exact build, I believe that it will work. Here are other options:

Marks - Attack Speed, will help phoenix jungling easily
Seals- Armor, again can help make him easier to play early game
Glyphs - MR/lvl is a MUST. While Udyr has a naturally high armor scaling, his MR is disastrous if trying to initiate a heavy AP team.
Quints - HP - for early game and easier jungling, Movespeed - if you want a little help chasing your enemy on top of your Bear Stance.

I like these masteries because I do not start at Blue Golem. If you have to start at the Blue Golem (no longer necessary following 1.0.0.120) then use a 0 21 9 mastery setup, taking utility mastery as your 9th point in utility. The 15% summoner spell reduction helps your smite cool down quite quickly, and gives you a good speedboost being able to pop ghost and chase someone down with the bear stance.

This skill sequence is designed to help you farm the jungle the fastest and be ready to gank and support lanes from level 4 on. Dragon should be able to be accomplished right after you get Wriggle's Lantern.

Each stance has its own purpose.
Phoenix is the best for farming/jungling.
Tiger puts out the most DPS on a single champion, assuming that they have not stacked armor.
Turtle helps your survivability, and when combined with the Spirit Visage allows you to farm yourself to full health quickly so you can stay in the Lanes/Jungle and stay out of the base.
Bear is the only way to initiate, and your most helpful skill to your teammates. Keep the enemy stunned and your teammates alive

Udyr has a great mid game for ganking. You get 2 early levels in Phoenix to farm the jungle. At level 4, you should be popping in between lanes, initiating with your Bear Stance and putting out as much dps as you can with Phoenix/Tiger dancing. The early spirit visage allows you to save points from turtle until the end. Bear Stance's stun does not increase in duration, and the extra movespeed is not needed as you will end up with over 400 movespeed BEFORE its activation. Leave this at level 3 (Udyr is the only champion that you can choose which skill ends up at level 3) and max everything else for maximum dps, shielding, and survivability.

The jungle path is the easiest and most dependable. You need no leashes or assistance, you can do this on your own.

Start at your banshees. When they spawn, smite the blue one and pop phoenix to finish off the 3 small ones. Use your health potion as soon as they hit you, continue using health potions as they each wear off, unless you are full health or almost full health.

Continue to Dual Golems, putting a point in turtle after you kill the first golem to help regain mana and save health.

Go to your wolves and kill these 3 with TURTLE to gain enough experience for level 3 and recover mana for your fight with the blue golem. Put the point into your Phoenix Stance for faster farming.

Kill your blue golem, dancing between phoenix and jungle as your passive is about to wear off. Watch your mana, make sure you reserve enough mana to end in phoenix stance to finish off the golem. Use Smite to finish him off.

Return to Banshee's camp and kill them, continuing to dual golems which should both spawn around the time you finish the Blue Golem.

If you have enough health to do so, kill the 2 small lizards in your red camp before returning to base for Madred's Razor.

You should now be level 4 and have Madred's Razor. Grab your red buff and begin ganking/lane support. Start with the lane that needs the most help, this means the lane where the enemy champions are being most aggressive, and initiate with bear stance for the stun, or ghost and then bear stance if you think you will have a hard time catching up to one of the enemy champions. As you make your way between lanes, farm the neutral minions as they spawn.

Continue until you get Wriggle's Lantern and then IMMEDIATELY ward and kill dragon. Try to end up around the dragon every time Wriggle's ward disappears to place another. Purchase wards every time you are in your base if you have enough spare gold, keep as much of the jungle warded as you can. Abuse Udyr's high movespeed and ability to pop bear stance to move faster and prevent your teammates from having to leave their lane to ward.

Udyr has a complex role in team fights. I came up with a list that Udyr should prioritize, meaning that you do the highest ranking item on this list first.

Udyr's Responsibility:

1. STUN CHANNELING CHAMPIONS (interrupt Katarina and Fiddlestick's ult. Anyone who channels or can be stunned out of their abilities is your first priority)
2. Stun Enemies who are chasing your teammates (If your carry is low health and there is a champion chasing him down to get the kill, especially Master Yi, stun them to protect your teammate and jump back into the fight)
3. Kite on low health (Save yourself when you are about to die. Keep switching between your Turtle and Bear Stances to run away, stacking Monkey's Agility and movespeed, along with your shield. You will often escape a team fight with under 100 health.)
4. Put out phoenix AOE damage (should have waves of fire to damage enemies at all times)
5. Attack the champion your team is focusing with Tiger Stance

Udyr has 2 "Dances." One is for damage, one is for defense. A "Dance" is when you continue switching between multiple stances to stack Monkey's agility and Activation abilities. The pairs of abilities that go well together are Phoenix/Tiger and Bear/Turtle. You use your Phoenix and Tiger activation effects to output your highest possible DPS. You should initiate this damage by starting with Phoenix and immediately switching to tiger if the enemy has high magic resistance but low armor, or initiate with Tiger and immediately switch to Phoenix if the enemy has high armor and low Magic Resistance. You use your Turtle to constantly create protective shields to soak up their damage, and you use your Bear to stun enemies every time you are able to, each enemy is able to be stunned every 5 seconds, you should keep mental track of how long it has been since you stunned your first champion.

ALWAYS INITIATE WITH BEAR. Use your movespeed to get to the enemy quickly, and the stun to keep em in place long enough to destroy them with Tiger/Phoenix combo.

WARNING: If you ever fall below 3 stacks of Monkey's Agility then you're doing it wrong. Keep switching abilities to maintain the extra AS and dodge chance.

I hope you enjoyed the guide. It is still being developed, please leave your feedback so I can make this better for the next reader or the next time you revisit it, there may or may not be cookies in it for you :o.