So technically, Twitch's R is a dodgeable version of Fishbones?

twitch r is way stronger

This is like comparing Karma Q and Caitlyn Q.

Piercing != aoe on target.

it could hit the 2 nexus turrets at once if aimed right

Twitch's R is like Jinx's rocket launcher auto attacks in the same way that Sivir's spellshield is like Nidalee's Q.

It isn't and they aren't even remotely comparable.

Jinx would have to have 400 BONUS ad for the damage from her rockets to be equal to Twitch's ult's damage. On top of that Twitch's ult gives him more range (out ranges towers) AND applies his passive (which leads into AoE contaminate/passive ticking damage). They are similar but Twitch's is so much better.