It will not learn it on its own. Just buy the TM or breed/tutor it.
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The only way Empoleon can learn Ice Beam is to buy the Tm from the Veilstone Game Corner
dragonair can learn ice beam any level
Lapras will learn Ice Beam at level 31.
It doesn't learn Ice Beam by level up. It can learn it by TM13 in all generations though.
At level 22 in Diamond and Pearl and level 18 in Platinum/HeartGold/SoulSilver. However, if you evolve it into Prinplup first, it is at level 24 for Diamond and Pearl and level 19 for Platinum/HeartGold/SoulSilver. Also, there's no reason to use a TM for Bubble Beam when you can teach it much more powerful attacks like Surf later on.