Dark matter has been a part of the "standard cosmological model" since the early 2000s. Robert Kirshner, who worked on cosmology from the supernovae side, notes in the epilogue to the revised edition of The Extravagant Universe how quickly both dark matter and dark energy became central to astronomy, astrophysics, and cosmology as a core assumption in such a brief time (between first edition 2002 and revised in 2004) mostly on the concordance between the supernova data, the galaxy clustering data, and the WMAP results. Since about 2008, I believe that some people started using the term "consensus model" to refer to a range of specific values for how much of each different component there is at the cosmological level. Look at any 2004+ paper from the Supernova Cosmology Paper for the use of the term and the values.So it is, specifically, a part of the SCM.
That definitely puts the onus on objecters to make their case.
The supernovae results fix the relative amount of matter and dark energy, but they put a lower limit on the amount of matter that is way, way higher than the limit on the amount of baryonic matter in the universe (what we think of as normal matter), as fixed by estimates from the relative abundances of the light elements. These limits are set out nicely in Peebles et al., "The case for the relativistic hot Big Bang cosmology", http://www.nature.com/nature/journal/v352/n6338/abs/352769a0.html . (I am sure that there is a free version of it somewhere, but I can't find it right now.)