Pros:

- Can be a tank and deal decent damage early/mid game
- Has on hit stuns making him great in team fights and a decent ganker
- Has a spammable speed boost that allows him to get to places fast
- Phoenix stance best for jungling and farming
- Has exceptional chase and escape with bear/turtle

Cons:

- Doesn't do much damage late game

Minor Con:

- Cant run away from Jarvans Ult, meaning jarvan can counter him

Tiger is only good for a few things, One purpose especially is to tear down turrets. Other than that not much, its first hit burst damage can be good for last hitting low health champions and it it does provide decent sustained damage and faster procs from wriggles so use it with phoenix when doing baron.

- AS Runes lets him jungle faster and deal more damage with phoenix procs while ganking
- Evasions Seals stack with his passive dodge chance; making him harder to hit and giving him 10% extra move speed if he dodges (Helps him escape even more).
- Move speed quints help to gank/chase and escape, very useful.

Possible substitute items are:

Randuins Omen instead of Sunfire Cape, the active is very helpful for chasing, but Udyr will lack damage and the aura stacks with his Phoenix stance making him do double damage with the cape, in addition sunfire gives more health but less armor so there are trade offs.

Force of Nature instead of Banshees, the move speed is very welcome, extra MR and health regen also good but lack of health to add to tankyness.

Trinity force is extremely useful and all the stats are good for udyr. attack damage, attack speed, ability power, procs between each stance and most important the movespeed.