Bastion

I laughed pretty hard when the pirateship comp worked in last year's world cup of Canada vs. S. Korea.
Bastion is 99% potato but has his niche moments where he is "Mr President" and if built around, is a beast :D

But.... now that the pirateship is a pretty established comp, people will expect it... be way to defend against is splitting up for a hammer/anvil approach (like widow/genji/tracer etc) if you're in a higher elo, or just brawler with high shields and spammage in lower (like orisa and junkrat)