>>18489469 (OP)German army milsurp flecktarn pants, with the pockets ironed flat (or any small-pattern camo with flat cargo pockets, or no cargo pockets at all).
A dark colored shirt, wine red? dark purple? or a light colored shirt with a dark colored necktie.
A clean, non-militaristic hair cut.
Black, non-glossy shoes, that aren't too big.
I'm not sure if that's suitable for a wedding though. Normally, the guests are not supposed to outshine the bride, and it'd be a pretty aggressive style either way.