What if the Pemalites were never wiped out by the Howlers--and, by extension the Chee never came to
Earth?
Dogs would never exist on Earth. The Animorphs would never have been able to pull off those off world missions without the Chee to stand in for them. A lot of battles would have been either impossible or extremely risky without the Chee, including saving Ax when he came down with the flu.
What if Cassie HADN'T given Tom the cube?
There would only be one morphing Yeerk as always. On the upside, they might never have discovered the advantage in giving certain Yeerks and the Taxxons the opportunity to take permanent morphs, thus freeing themselves of servitude.
What if David really DID kill Tobias?
Rachel would have had eagle for dinner. Or killer whale. Or lion or mouse. He'd be a dead man, basically. In real life I imagine the fans would have cried out for blood and Applegate would have lost about half of her readers. But Joss Whedon is known to kill off major characters in a long running series so I don't think it would have totally crippled her.
What if Tobias had been the only one to meet Elfangor?
Pretty much what happened in MM 4: Back to Before only Tobias would have either wound up dead, a nothlit, or worse case scenario, another Controller.
What if Ellimist and Crayak played chess, instead?
Counter question. How friggen cool would it be if programmers made a game like the one Toomin and his species played?
What if it was Melissa, instead of Rachel (in a time that wasn't altered by the Time Matrix?)
I really do wonder about this one. Melissa would have made more sense in the Ellemist's scheme, since Iniss 226 (Chapman's Yeerk) was a high ranking officer who frequently communicated with Visser Three. But in the current timeline, with all that was going on, she would have been a liabilty. Even Visser Three, as high on himself as he was in The Visitor, couldn't ignore the fact that the "Andalite Bandits" always managed to twart a plan that he had discussed with Iniss 226 that very day.
What if the Animorphs had said yes in the Stranger?
Someone answered this one all ready. And for my money it would have still been irrelevant. Ellemist was using the entire set up as an excuse to show them the tower where the Earth based Kandrona was located.
My What Ifs:
What if the Andalites knew about Hork-Bajir Seers?
If the Arn could engineer themselves to die when the Yeerks infested them, why not mass engineer Seers so that the Hork-Bajir would have a better chance of fighting back?
What if Tobias had grown up with his mother?
What if Rachel had been the leader from the beginning?