Say I had 6 copies of Adrix and Nev, Twincasters (AN) in play and I had Nightpack Ambusher (NA) trigger, and I turned the 2/2 wolves into non-legendary copies of AN, via Esix, Fractal Bloom. How many copies of AN would I end turn with? To add, how would multiple NAs affect Esix's ability?
In general, if you control Esix as well as M permanents with Adrix and Nev's abilities, didn't create any tokens yet this turn, and would create N "2/2 green Wolf creature token(s)", instead you create N * 2^M tokens, all of which are either—
copies of a creature other than Esix of your choice, or
2/2 (nonlegendary) green Wolf creatures,
your choice. Thus, it's not possible here for some but not all of those tokens to be copies of Adrix and Nev, for example. Observe that Adrix and Nev's replacement effect changes only how many tokens are created, not what each such token is. (See also C.R. 614.5.)
(Note that neither Esix's second ability nor Adrix and Nev's second ability is a triggered ability — both abilities lack the words "when", "whenever", and "at" [C.R. 603.1]. Note also that neither ability changes the tokens to be nonlegendary, and neither does Nightpack Ambusher's last ability. Compare with Helm of the Host.)
In the case of multiple Nightpack Ambusher permanents, consider this scenario:
You control two Nightpack Ambusher permanents, Esix, and M Adrix and Nev permanents (all of which are creatures and no more than one of which is legendary, where M is two or more) during your turn and didn't cast a spell or create any tokens yet this turn. Your end step begins, so each Nightpack Ambusher's last ability triggers. You put those abilities on the stack.
All players pass, then a Nightmare Ambusher ability resolves. You would create a "2/2 green Wolf creature token", but instead you create 1 * 2^M tokens, all of which are either copies of a creature other than Esix of your choice, or 2/2 (nonlegendary) green Wolf creatures, your choice. Assume you have them be copies of a nonlegendary Adrix and Nev creature you control. The ability leaves the stack.
All players pass, then a Nightmare Ambusher ability resolves. You would create a "2/2 green Wolf creature token", but because you control M+2^M Adrix and Nev permanents, instead you create 1 * 2^(M+2^M) of them. (Esix doesn't apply here because you've already created one or more tokens this turn.) The ability leaves the stack.
(Note that neither Esix's second ability nor Adrix and Nev's second ability is a triggered ability — both abilities lack the words "when", "whenever", and "at" [C.R. 603.1]. Note also that neither ability changes the tokens to be nonlegendary, and neither does Nightpack Ambusher's last ability. Compare with Helm of the Host.)
In the case of multiple Nightpack Ambusher permanents, consider this scenario: