I was going to add a note about Tosen when I answered the previous question but decided not to since I couldn't remember if Tosen's garganta was an elipse or not. Anyway, here's the most likely answer for Tosen - he's a Shinigami-Hollow hybrid. All the Shinigami who opened the garganta were pure Shinigami: Urahara, Mayuri, Aizen. Now we don't know when exactly Tosen became a Shinigami-Hollow hybrid. But it is reasonable to assumption to make that Tosen had gained hollow powers by then and used hollow techniques and not kido to open the garganta.