Cyclone Idai cannot be blamed on climate change, but the scale of the disaster probably can be. Climate change is predicted to intensify climatic events, making extreme events worse - both droughts and heavy rain and floods will be more severe. In particular, global warming will not increase the number of cyclones, but will make them more intense. In the Mozambique Channel, this is because the sea water is getting warmer which gives the storms more energy.
Mozambique normally sees one or two cyclones a year and they normally come north up the Mozambique Channel. Storms are only named when they become strong, and those that come up the Channel are usually already named.
What became Idai was an ordinary rainy season tropical depression which passed over Zambezia into Malawi, then did a u-turn and returned to the Mozambique Channel. Unusual, but not unprecedented. It then sat in the Mozambique Channel for nearly a week, sucking up warm water and energy, becoming a category 3 cyclone. That appears to be unprecedented off the coast of Mozambique, and was probably caused by the warmer sea caused by global warming. South African and other scientists are now running models to see what caused the unexpected formation of a cyclone, and may be able to see if climate change was the cause.