Yay? Nay? Anything I could do to improve it?
Sadly, tanking with Beartic will be difficult in any tier, thanks to one major weakness; it's typing.
Ice typing may be pretty good offensively, but when trying to tank, it's got a countless amount of weaknesses, and only one resistance to make up for it. It's vulnerable to spikes and toxic spikes, and worse yet, loses 25% of it's health whenever it swaps into Earthquake.
Also, cases were 252/def/252sp.def is better then 252 HP/the rest being spread into the other defenses is very rare, since HP does more to help then each individual defense. Rest is also difficult to pull off now, as every time Beartic will swap out, it's reset, so you'll have to wait two more rounds for it to wake up.
Beartic should best be used offensively, rather it's 252 att/252 Speed or 252 HP/252 Att, it's all about hitting as hard as you can.
Speaking of which, a choice band set hasn't been done, so I may as well do one.
Beartic @ Choice Band
252 HP/252 Att or 252 att/252 speed
Adamant
-Icicle Crash
-Super Power
-Stone Edge
-Night Slash
The first thing you need to know is that this set needs a rapid spinner or magic bouncer. All sets really, really want one, but a choice band is practically doomed without one. Icicle Crash is an excelent STAB attack, while Super Power hits those steel type swap ins. Stone Edge rounds the coverage by hitting fire types trying to swap in on Icicle Crash, and Night Slash is just filler.
If you go for maximum speed, make sure it's on a rain dance team. If not, go for HP. Unless, you intend to use this to counter rain teams in OU, but, uh, good luck with that. If you want to use this thing in that tier, you're gonna need it.