Ultron is barely a support as is so I can see Dave flexing on him just because it's not really a strategist and he feels cool. As for the Spiderman question, I think it's 100% John and he's also bad at Spiderman. He is the spiderman who goes 0/10 trying to dive and failing somehow.

Alternatively for the Trolls it's Gamzee and he never swaps off he is a certified Spiderman one trick