Sorry for the question, but I could not find an answer while searching the site.
If you select 3 team-ups for your team, while on defense how is it determined which will be used by your team? For example, is it the center selection, or is it just a random team-up not chosen by you? Thanks.
On defense it’s just a random team-up.
Random as in from the game library or random from the 3 you select? Thanks for the response.
The first option, a random one from some big list.
Though, sometimes in pvp, it certainly feels like the game picked just the right team-up against my team and then used it at the worst possible moment for me … 
Like when you don’t notice the AI has a Loki black TU and it flips your buffed strike tiles to their defense and now you’re hitting the AI for 1 damage… nope, never happened to me 
I thought maybe your choices were the ones used on defense, because the team-ups used against me in pvp so often seemed to work well for my opponents team.
Or Punisher’s Retribution taking out 5-star Thor… 
It’s a mystery wrapped in a riddle inside an enigma.
If ever I am running a team who need green AP, the AI will always have a purple Red Hulk team-up. And you had better believe they get to fire it.
Right up there with enemy Prof 5 always seeming to get that 4-match waiting for them on their next turn.
Or if you’re playing against a team with Teen Jean, immediately bet $5 there will be a match 5 waiting for you on the opening board (which happens .005% of the time otherwise).