This set for udyr is one of the best sets you can use. It looks strange at first but you will be destroying enemies in seconds with this set. This set is based on Attack Speed, Crit and quick damage.

You will want to go with attack speed marks to add to the set, armor seals and magic resist glyphs will let you dive into fights easier. Quints can be whatever you want but i would use crit quintessences.

Masteries will base on attack speed, attack damage, added armor and magic resist and movement speed.

The boots of mobility will allow you to catch up to enemies or gank very quick, the feral flare will let you jungle very easily and 33% of the damage applies to champions. The main items of the set are the 2 phantom dancers which will let you attack so quick, with the added crit and damage from the infinity edge and black cleaver, that you will destroy enemies in seconds.

As a jungler you always go with smite, but exhaust will let you catch enemies quicker.

Pros -You attack so fast and crit so often along with the damage you destroy enemies in seconds [literally].
-You move quick enough to catch enemies easily.
-Your stun in bear stance then a follow up tiger stance will make finishing enemies easy.
-The feral flare will let you jungle easier and 33% of the damage applies to champions.

Cons -Some champions can take you out easy if you dont catch them off guard [ex. yasuo].
-You dont move very fast without the boots of mobility [dont forget to get them after the feral flare].

Ganking is made very easy with this set to assist allies. You stun with bear stance and a follow up tiger stance will let you and your ally burn right through the enemy. Tiger stance with a follow up turtle stance on minions or jungle will let you get quick lifesteal. Pheonix stance is only used for minions and jungle, not very useful on champions for this set.

To sum everything up, You attack so fast and crit so often along with the added damage, you jungle very easy, you can gank easier, you can catch enemies off guard easy with the movement speed bonus from the boots of mobility and your very good at taking enemies out quickly.