The tag implication #51399 classic_knuckles -> knuckles_the_echidna has been rejected.
Reason: classic_sonic implicates sonic_the_hedgehog, and classic_tails implicates miles_prower.
But those implications are not currently in place for Amy and Knuckles.
EDIT: Some discussion about this has been going on in the Amy Rose version of this thread: topic #39477
EDIT: The tag implication classic_knuckles -> knuckles_the_echidna (forum #371214) has been rejected by @slyroon.
Updated by auto moderator