Nolimar (also known as Solimar or Lolimar) refers to the practice of using Olimar without any Pikmin, either due to losing Pikmin from being KO'd, or by choosing to play the entire match with no Pikmin.
Without Pikmin, Olimar only has six attacks: his neutral attack's two hits, his three tilts, his dash attack, and his neutral aerial. Nolimar is capable of racking up damage with most of these moves, with his foward tilt and dash attack being his "KO" moves. Combined with the hop from a blank Pikmin Chain and the launch resistance of Pikmin Order, it is possible to win a match as Nolimar despite his pitiful KO power and major problems with stale moves; of course this is incredibly difficult.
Note that at the start of a match, Olimar will automatically pluck three Pikmin during his entrance, so to intentionally play as Nolimar, the player will have to use Pikmin Throw or his forward smash to throw the Pikmin off of the stage, have the Pikmin attacked, have Olimar KO'd, or simply choose to never use Pikmin-based attacks.
Nolimar is a popular character to use in gag matches/taunt matches.