The Tick is easy. M&M doesnt care whether its armor, skin, force fields, the saves all mean the same thing. Arthur would be up to the players, but I'd call him a sidekick. Give him "Jumping: Limited to buildings"
Swamp Thing can use a variable power pool, like Magic, to purchase all his effects as alternate powers of "One with the Green" including teleport(limited, through green), regeneration(Limited, touching green only) etc. Absolutely not difficult to model. In fact, all the DC characters are already done in a pdf.
Anyone who claims powers cannot be modelled in M&M just has never looked at the book. Its clear to me that people who love Hero have never so much as looked at M&M, because its power gen system is fullbore, and it can do anything. I am fine with people having specific complaints(which I am fairly sure I can dispel) but making up stuff about a system you've never read is not necessary.
I've made characters for Champions, and I've made characters for M&M, and M&M is both easier, and more robust. It also doesnt require a scientific calculator, or 200 points of disadvantages, like Champions does, and from the sounds of it, like Hero does.
Mutants and Masterminds is incredible. Its a better use of d20 than D&D if you ask me.
Also, yes, I'm a fanboy.