Udyr Needs a Rework and Here's Why
Now, I will preface this by acknowledging ahead of time that there are a lot of people that enjoy Udyr as he is either for his gameplay or overall design. I'm not advocating that Riot remove his identity, merely give it an upgrade and a means of having more depth.
As Udyr is right now and pretty much since his release, he is a "Press X button to add on hit effect". That is literally all he is mechanically speaking when putting passive bonuses aside. He lacks any depth beyond running up and striking you with an attack and most of his gameplay revolves around cycling through these abilities. For as bad as a rep that Riven receives for a "mash buttons to make things happy" character, Udyr is by far the worst offender. What makes this particularly bad is that the role is already filled and to a much better effect: Sona.
Udyr is said to be a "stance" based character, but that's really just being generous. Udyr is perhaps the most barebones stance based character I've seen in a MOBA to date... And I think he can be done a lot more justice; be innovated in a way that wouldn't upset fans and would make those disinterested in his playstyle more forgiving.
Let's start with his ability effects. These will not have to change. Running with the reworks Riot has been doing as of recent, the payoff of his abilities should not be changed. One ability will stun, another will cause D.O.T., one will heal him, etc. In functionality is where he needs to be upgraded. As a "Stance" character, make him MORE of a stance character. When he changes styles, make the rest of his abilities mechanics change as well.
For example, his E could normally be a short range skill shot to some degree that stuns on hit. However, if you're currently under the effects of his Q, changing to his E will instead become right click centric and will only stun after a few hits, but during that time he'll be granted attack speed for the duration. Swapping from W to E will cause him to be shrouded in an effect that will stun the next person that harms him.
These are all hypotheticals, but I think this is the general direction Udyr should be taken in. Rather than just cycling mindlessly through his abilities, the stance changes should have legitimate thought put into them before being put into practice. How you cycle through his abilities should change based on the situation. For a character that is supposedly a martial artist, he should reflect it a bit more in practice.
As for his design, his artwork really isn't that bad. Overall, he merely needs a model update and overworks to his Ability Icons and and maybe some splashart edits or updates. In terms of how his model is in its current state, why is a "martial artist" (Yeah, as a martial artist, I will pick on him for this subject) constantly remaining in a statuesque position with his arms at his sides? This makes him look silly for lack of a better word.
These are pretty much all of my main concerns and areas I'd like to see improved upon. I would bring up his lore and how convoluted it is, but League has a running history of wacky lores and I think that adds to the game somewhat.