Nintendo only own 30% of Pokemon company. Nintendo owns the licenses though, but they just let Pokemon publish them and PR things. Maybe they o the same to Bandai, buys 20-30% to get to be the boss and get the exclusives.

And I did some research, and bandai share costs 2850 yen, and 100% of Bandai would cost little less than 1.3billion. So Nintendo could afford them, but they probably will buy just little bit, if any. Reuters writes about this too, and they are pretty reliable.