the Gai that fought Madara opened the 6th gate fore long periods of time to put up with Biju... he also opened the seventh 3 times and used Hirudora 3 times.... he had colllapse 3 times he also fought Biju, Obito, Madara, 7 Swordsmen of mist, countless zetsu and so on... clearly under 25% and yet he still almost KILLED a fresh Juubidara.... so at 100% I am sure he can do significant damage to ANY NV Shinobi