Baku is a non factor sucking manda is like a giant noodle longer than its own body also chewing on him is bad since it has human teeth manda body is not going to crush like that snake's body are like tangy beef jerkie and if he's chewing he stops sucking giving manda his moving space baku is constricted by manda when this happens also manda goes underground at very fast speeds and if it trys to suck manda could easily open its mouth
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and its baku face putting baku in a genjutsu takes a second considering sasuke summoned manda than put it in a genjutsu before deidara C0 explsion killed him genjutsu takes little to no chakra to do. Danzo never laugh at sasuke's genjutsu before he doesnt now sasuke counters danzo wind shuriken with his katon shuriken
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also he has much to many shuriken for danzo to try to compete