I don't think Udyr needs stacking cdr, in regards to his pbe changes
While cdr, is certainly nice on udyr, he gets more than enough of it from items. Trinity force is pretty core on any version of udyr, which gives 20%, and most resist items gives atleast 10%, so that stacking cdr from passive is not doing much for him.. Instead could you give udyr a flat amount of armor/mr, stacking up to 5 times, lets say 5 armor/5 mr per stack, or a % stacking bonus of total resists. That way as a champion with no gap closers, he could truely shine in extended fights, and fullfill his duelist/fighter role better.