Offical names for Plutoids must have a mythological origin. It joins previously named plutoids Pluto and Eris, and previously named dwarf planet Ceres. Makemake is the largest object in the solar system named for a non-Western mythological figure.
Most known plutoids were discovered by astronomer Mike Brown and his team. His website notes that the smallest round satellite in the solar system has a diameter of about 400 km, and that the smallest round non-satellite in the solar system, Ceres, is about 900 km in diameter, which, he suggested are the empirical cutoffs for icy and rocky bodies, respectively, to form spheres with their own gravity.
Prior to today, Makemake was the largest object in the solar system without an official common name, and without formal recognition as a dwarf planet or satellite.
Some of the other leading contenders in the queue to be recognized as dwarf planets, with their diameters in kilometers, approximate locations and their official or unofficial common names, where available, are:
Santa (Posible Dwarf Planet Kuiper Belt) 1,500
2002 TC302 (Possible Dwarf Planet ca. Kuiper Belt) under 1,200
Sedna (Possible Dwarf Planet ca. Kuiper Belt) 1,180-1,800
Quaoar (Possible Dwarf Planet Kuiper Belt) 989-1346
Orcus (Possible Dwarf Planet Trans-Neptune) 880-1880
Wikipedia has a more complete list.
Ceres, in the asteroid belt, is the only dwarf planet which is not a plutoid, although some modern researchers believe that Ceres may have once been a plutoid before being catapulted by gravity into the inner solar system during the process by which the gas giants took their current positions in the solar system. It is much larger than its three nearest rivals in size in the asteroid belt, which together with Ceres make up about half of the mass of the main asteroid belt.
Other large bodies in the solar system include the Sun, eight full fledged planets, and fifteen dwarf planet sized or larger satellites of planets. Another blogger more completely summarizes (wiht the inaccuracy of counting Ceres as a plutoid) the state of affairs as follow:
For those keeping count, the official tally for our system is now four stony planets, four gas giants, four plutoids, around 180 moons, 1000 Kuiper belt objects, 3500 comets, and 10,000 asteroids with about seven more plutoid candidates under consideration and a few dozen believed to exist.
Objects that are much smaller than Orcus are unlikely to become dwarf planets, as opposed to comets or asteroids, because they tend to lack sufficient gravity to compress themselves into a roughly spherical shape, which is part of the definition of a dwarf planet.