I had to comment on that one,
Udyr is the least of the problems actually, he is just totally annoying and just the last year's changes in the game made him very strong, it is easy to lose track of balance when you add something into a game or change the overall itemization, especially that.
Anyway he is just annoying in my opinion, you can chase him on the whole map and still not be able to catch him, in my opinion master yi should outrun all of those champions because he lacks tankines which is something udyr can have.
One thing I hate in the game is underpowered champions, instead of making champions weaker why not make other champions stronger?
I mean take for example Azir which in the casual hands feels weak. The stronger mid laners in my opinion are at the moment ahri, lux, zed.
Considering I play veigar because I like mid/late game hyper-scaling, I get poked so much from ahri. It is a mage with a strong CC but at the same time it is a skillshot, she feels not over powered in sense of balance but her utility/damage kit is strong, talon is strong too but falls off quickly and its a wasted slot if he is not getting fed early.
I personally like unique kits like
singed,
jhin (he is a ranged assassin and not adc, he gives the impression that he is OP yet he needs help),
azir (well... yeah we need to look into that more),
graves (very strong but if bullets get tanked he gets denied),
Leblanc (sorta fun to play),
Poppy (needs some help as well, unique yet situation-ally strong, more of a counter champion).
Kassadin (unique way to be a mage K-assassin using an enhanced blade, blinking around is fun and now more balanced...oh season 1... )
To sum up some champions need help, like Vladimir to feel more enjoyable to play, essentially you press 2 buttons all the time and either get kills and HP or stay around and wait for a kill or dive and die. I like the concept of Aoe damage in team fights when using a mage, now he may be a bit tankier than other mages (3000hp with full ap build average) but he feels like the old poppy. I like the fact that he plays TOP and Mid though, I also like the concept of infinite sustain and use Hp management to do damage, I know he is not a vampire but a blood-Bender though I would like to see a vampire character arise from the lore, I know its cliche but some people actually like this.
Also Azir feels not so easy to play when playing casually or ranked, it is not an easy champion to use but at the same time it punishes players that attempt to master him from early on even with experience in the game and in league. Aatrox is the same way, for example I can play yasuo but I cannot play Aatrox or Azir but I like them both and the result is a harsh game and very punishing. So you end up farming and waiting for items to keep you intact.
An idea I have for Singed this time is his poison damage should scale off max% Hp per 5 sec (stacking/refreshing the longer you stay in poison) and remove the Ap scale. This for making him a champion that the longer you stay near him the worse it becomes. But this is a balance if you think about it, tanks tend to buy MR so they will take less damage and Low hp champions like lux will take a fixed value of damage. So basically the poison will sort of balance the Hp bars of the opponents, you do the math of course. He could have a %magic pen passive on his ult to do damage to tanks too of course. This champion for some reason is one that in every game I see feeds the enemies and laughs like a maniac but he feels unique and creates a hidden rule in the game (Never...ever chase singed), he is only annoying though and skill lever impacts what he can do and how good he is as a champion.