It was also never said that BLU would have to do EX Trials and Coil in order to go and learn spells.
All was said about group content was that they could group up with other BLU's in order to do this content.
Outside of this, everything said about BLU was specifically in regards to them being a solo job that doesn't need nor work very well in group content.
This, includes their reasoning for making their weapon not have stats, so that BLU's wouldn't feel as though they needed to farm dungeons in order to get weapon upgrades.
To take away nothing in regards to their official reveal trailer having a BLU solo Shiva.
Unless you can also point out where on this slide they specifically mention solo only for overworld and Carnivale:
https://pbs.twimg.com/media/DsPvbAcVAAAcbkW.jpg
