Sarah Steele gets her first and second attacks at her first tier, but all other Kraken Skulls companions get their second attack at their second tier. Kinda makes Sarah Steele overpowered compared to the others.
However, please be aware that the animations have nothing to do with the balance of any character. Just because a character does not have 2, 3, or 4 basic attacks or multiple critical tier animations does NOT mean that character can't deal as much damage as any other character.
When a character has a lot of animations available, we map different amounts of damage to different animations.
If you think of each hit on a scale of 1-10, with 10 being the most awesome hit for the most damage, some characters might have an animation only for a "1" and a "7." He can still deal any amount of damage from 1 to 10, but we only have two animations mapped into that range. Any hit from 1-6 we show animation A, and all the hits from 7-10 we show animation B.
A more fully fleshed out character might have animations at 1, 3, 5, 7, 8, 9, and 10.
That's a simplification but I hope it helps.
Sarah Steele has always been a strange case because we remodeled her so many times, trying hard to get her "just right!"