Hmm. In the type of anime
I love (I.E. Shojo, magical or superheroic shonen):
-Yes, Visser One's Hot Motherness would get downright preposterous. And her boobs would be bigger.
But she'd also become a far more sympathetic character than she already was, an antiheroine if you will.
-Visser Three would never suffer Villain Decay and his thought speech would sound like Estrogen Brigade Bait. He would seem far more powerful than he theoretically should be and he would wipe the floor with the Animorphs a couple times. If Jake is main character, their relationship is closer and very strange.
- Jake would become illogically stoic and competant, though we as viewers would see his true thoughts. Rachel's tsundere nature would become worse as noted and her relationship with Tobias would be emphasized. Cassie would have even less personality. They'd spend a lot more time in school and they'd have more problems there. And they'd begin at a later age.
-Yeerk politics would become even more layered and emotionally charged. The Council of Thirteen wouldn't be as secretive, and they'd have a very odd power dynamic going on. We'd actually meet the Yeerk Emperor, and he'd turn out to be the creepiest person on the "show."
-The Animorphs would be more powerful and do too much damage to the Yeerks to make sense, or at least Visser Three himself. Many anime of the type I love are character development shows that empower teenagers.
-The Ellimist would make even less sense and would speak in psuedo-philosophical bull. This really airy, holy music would play whenever he got involved (Played Skyward Sword? ) and the audience would get the sense the Animorphs were involved in something of great import.