Spot on. BRICS/SCO is all about the power of China and Russia. Rest are just add-ons. Remove Russia and China from BRICS/SCO and the organisation is irrelevant.
China and Russia together provide the economic, financial, technological, military, diplomatic, natural resources, geopolitical power. China’s greatest ally is Russia. Russia’s greatest ally is China.
As for creating a trading currency, China and Russia should create one together first and other countries can join it whenever they are ready.
India, Brazil, South Africa are easily manipulated by the West. They will be obstacles to creating anything that curtails the power of the West.
Outside China and Russia, I would only trust Iran.