Yes. Al you need to do is catch either one of the pokemon mentioned, for example Archen, then get a friend to trade from black -> black or white -> black with the other pokemon (in this case Tirtouga) to you.
No.
Archen is way better.
there is a backpacker in relic castle who will give you either a plume fossil (which is revived into an archen) or a cover fossil (which is revived into a tirtouga)
When breeding, the egg will always be the same species as the mother (the only way to get around this is by using ditto). If you have a male archen (which is likely, because archen is usually male), you're out of luck and will just have to wait until you can acquire a ditto.
Unlike Pokemon Pearl/Diamond with its extravagant variety of Fossils, Black/White Version has approximately 2 Fossils. There is possibly more but I never encountered those. You can get Fossils at the Relic Castle and there will be a lady probably at the first entrance and you will be asked if you want a Fossil out of two Fossils. One of them is a Flying/Rock Type, which is Archen. Archen is unable to use Fly until the second evolution (Which is the last evolution when it hits its second evolution). Second Pokemon you can get from the lady in the Relic Castle probabilistically on the first floor where you enter, is Tirtouga. Tirtouga is Water/Rock Type. If you have Oshawott as your Beginner Pokemon then I suggest not to get him. To revive these Pokemon from its rock Fossil you must go to the Nacrene Museum (Which is in Nacrene City) where the City Gym Leader, Lenora, the Archeologist with a backbone, is.
To get Tirtouga, you must travel to the Relic Castle, to the west of the construction yard between Castelia and Nimbasa. In the Relic Castle you will find a Hiker who will give you a fossil of your choice. You can choose the Cover Fossil which will turn into Tirtouga, or the Plume fossil which will turn into Archen.
trade with someone
Zorua,reshiram,tirtouga,archen
Cover Fossil is Tirtouga. Plume Fossil is Archen.
Tirtouga from the Cover fossil, and Archen from the Plume fossil.
Archen is way better.
There is a lady with a backpack on she gives you either a plume fossil(Archen) or a cover fossil(tirtouga)
tirtouga evolves into carracosta at level 37. if you wanted to know this too, archen evolves into archeops at the same level as tirtouga to carracosta
You need to go to relic castle and the backpacker will give you a Tirtouga or Archen fossil.
No.
You can only get one. Unless you have an action replay and pokemon modifier for it. You can also just trade one of them from pokemon Black version. I hope you like my answer Rayquaza394
so many of them like tirtouga ----> carracosta and my other eevee evolves into 7 of different pokemon archen--->archeops vullaby--->mandibuzz purloinn-->liepard and othars
there is a backpacker in relic castle who will give you either a plume fossil (which is revived into an archen) or a cover fossil (which is revived into a tirtouga)