What legions did Trajan take to Dacia?

[D B Campbell]

It is true that there is no direct evidence of legion’s existance after 70 AD nor of its presense in Moesia.

'nuff said!

But there is a Tacitus’s passage (Hist.III 46), where he wrote, that in that year detachements of the former Vitellian’s army were attached to a new governor of Moesia, Fonteius Agrippa. E. Ritterling in his article stated that among these troops was legio V Alaudae (Legio, 1925, 1569) or, to be precise, that part of the legion which fought in Cremona with its aquila.

Tacitus (Hist. 3.46) simply states that "troops were added from the army of Vitellius" (additis copiis e Vitelliano exercitu) to the garrison of Moesia. This gives the impression of a rag-tag collection of soldiers, sent to make up the numbers in other regiments, rather than the "detachments" that you mention, Centurio.
Although Tacitus mentions legions wherever possible, there is no mention of V Alaudae here. It takes a giant leap of faith (imho) to assume that Tacitus' copia in Hist. 3.46 were not only an entire legion, but specifically V Alaudae.

Furthermore, there is an insciption found in Dobrudgea (CIL.III.14214=ILS.9107) with the names of soldiers killed in battle ... Judging by birthplaces of the soldiers listed in this inscription, they once may belonged to a Rhine Army, part of which was legio V Alaudae.

The (badly fragmented) inscription lists two men from Gallia Narbonensis (Forum Iulii and Vienna), one from Germania Inferior (Agrippina), and three from elsewhere (Cemenelum, Celeia, Iuvavum). The inscription has never been securely dated, and it was only a theory of Ritterling's that it was erected in AD 86. Crucially, there is no mention of V Alaudae.

These two sources, literary and epigraphical, seems to be an indirect evidence of legion’s existanse after 70 AD and its dissapearence from the army lists after being destroyed on the Danube.

In my opinion, this is faulty logic. We know that several other legions disappeared in AD 70 and are never heard of again. We never hear of V Alaudae again, either. (And we all know how Occam's Razor works on RAT! )