[Starscreamer]

hmmm...there is one thing about Kabuto we haven't mentioned this whole time that may give him an edge...not his offensive ability...but his DEFENSIVE. OOOs could rush him with the gorilla arms, but Tendo could cast ON, go back to rider armor, and pretty much take the beating. Cast off again, use the shrapnel to distract, and just straight Rider Kick.
If he summons the Zechters for the perfect Zechter they also can act as interference, much like Shotaro with his stag phone.
Finally, this is really going to nit pick from the show...BUT he also has that weapon that launches a SWARM of explosive mini beetles. 100 OOOs clones? 1000 little flying seek and destroy bombs.
and the final option...Tendo just makes the perfect ice cream bar and Ank falls head over heel in love with it, and makes OOOs surrender...