In order to perform Edo Tensai,you need a host.While Kabuto illustrated how Edo Tensai is performed to Obito,you must have noticed that Kabuto used a host for it.
Once the ET is successful, the body will retain the properties of Edo Tensai jutsu ,i.e the body cannot be destroyed(for instance,if the body is cut or if it was pierced,it would wrap itself with tiny bits of paper,it cannot be felt by the reanimated souls).
But the host(which is present inside ET's body) does contain the blood.With help of that,any person ,under the influence of ET, can perform Kuchiyose No Justu. Don't forget that Edo Tensai is a part of Kuchiyose No Jutsu.
Mizukage is a high level shinobi for which he doesn't need to perform any handseals.
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