First, the passage in Mark 16:9-20 is highly disputed and many do NOT believe it should be part of the Biblical canon. However, for the sake of this question, let us consider the text without the matter of textual criticism.
The text of Mark 16:17 lists several phenomena:
And these signs will accompany those who believe:
- In My name they will drive out demons [See also Luke 10:17]
- they will speak in new tongues [See Acts 2:1-4, 1 Cor 14]
- they will pick up snakes with their hands [See Acts 28:3-5]
- and if they drink any deadly poison, it will not harm them
- they will lay their hands on the sick, and they will be made well [See James 5:13-15 and the many healings in Acts, etc]
Thus, the list of "wonders" in Mark 16 mostly has fulfilments in other places in the NT. i could not find an instance involving poison. However, we have plenty of instances where the word is used as a metaphor such as, James 3:8, Acts 8:23, 14:2, Rom 3:13, Heb 12:15, etc.
Note that the text of Mark 16:17 does NOT say that such signs would apply to ALL believers but simply "accompany" those who believe - ie, be manifest among believers - some would have different spiritual gifts to do such things. See 1 Cor 14.