Great hatches! The offensive Lapras has high enough CP to demolish a 3000 CP Dragonite. If you raise it's CP to over 2000 you can destroy probably two 3000 CP dragonites if you dodge. If you don't have any Dragonite killers such as a Dragonite or cloyster or dewgon then maybe you should power up the offensive Lapras to take on two dragonites in a gym. If you do have other offensive Dragonite counters then I would power up the defensive Lapras to place higher at a gym and in the meantime use the other Lapras as a buddy.
Lapras Power Up Question
A few weeks ago I hatched a Lapras with ice shard/ice beam. It has 87% ivs. Since hatching I have powered it up from level 20 to 28.5. Here it is,
http://imgur.com/WP2oGiD
Today to my disbelief I hatched another Lapras and this one came with the ideal offensive move set frost breath/blizzard. There are 4 possible iv combinations, 82.2%, 84.4%, 86.7%, 88.9% Here it is,
http://imgur.com/LnoEFPx
I mostly want Lapras as a Dragonite destroyer. Should I keep powering up the first one as it is already a higher level now or should I prioritise the second one as it has the best moveset.?
Thanks in advance for replies :)

Answers
The newer one has the better moveset (FB/B) but IS/IB is by no means unusable.
With your current candies you can take the level 20 one to 24, although the level 28.5 IS/IB should still be stronger just because it's got higher level, since Laprases ice movesets are all fairly close to each other in effectiveness. (we don't talk about Dragon Pulse).
If you feel like the IS/IB one isn't enough to destroy Dragonites with as it is currently, or it's constantly in gyms, then powering up the new FB/B one past 28 will make it a better Dragonite destroyer.
Don't worry about using the lower CP Lapras for training, because if you bring a 1600 Lapras to train against a 3k Dragonite, you need to get through the ~2k CP Pokemon at the bottom of the gym first, and if you bring a 1665 Lapras to your party, that'll greatly reduce your prestige gain against the 2k CPs.
It's just more efficient in both time and potions to train with and against lower CP Pokemon, fights are quicker and you'd probably only need a Super Potion (maybe a regular too) to heal them to full while the Lapras would need Hypers.
If you have a 3000+ CP Dragonite a 1600 CP Lapras is its partner. Take down a gym, put in your Dragonite, prestige it up to open 3,4,5,6, or 7 slots with the Lapras or until the spots get filled. No sh/t you shouldn't use a Lapras through a gym with 2000 CP mons for prestiging. I do this all the time. Works like a charm.