Japan takes the cake for cetacean species.
Okinawa Churaumi Aquarium houses Pacific and Indo Pacific Bottlenose, Rough Toothed, Pantropical Spotted, and Pacific White Sided Dolphin, and Pseudorca, for 6 species total.
Yokohama Hakkeijima Sea Paradise houses Pacific Bottlenose, Pacific White Sided, Commerson's, Pseudorca, Short Finned Pilot Whale, and Beluga, also for 6 species.
Chimelong Ocean Kingdom in China also is a powerhouse, housing Pacific Bottlenose, Pacific White Sided, Indo-Pacific Bottlenose, Indo-Pacific Humpback, Pantropical Spotted, Pseudorca, Beluga, and Orca for a whopping 8 different species!
In North America, the Seaworlds and Vancouver Aquarium have the most variety.