This is likely mostly down to the license, of course, but the Spider Man IP holds quite a lot of weight as well
When building a deck like Mewtwo ex, its good to look at alternative lists
All of this is worth bringing up, in my opinion, because I want to let people know that if you want a Protean Hulk combo in your 75% deck its going to be a very difficult process and I basically determined it wasnt really worth trying

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if you do, you then get to put three +1/+1 counters onto Ob Nixilis