Tails or Knuckles?

[Rökkan]

edit: and tails is in a mech for pretty much all of the adventure games, he doesn't have very good non-mech abilities aside from, well, flying

you mean pretty much all of the second adventure
because there's only two scenes (and a half) where Tails in in the Tornado in the first one
aside from mechanical abilities (like bombs, robots and all), I agree that he pretty much doesn't have any other ability outside flying and... waving his tails