By definition these types usually are just a marketing ploy, that's literally the reason why Godzilla and Kong crossed over in the 60s, but I still think many of them are great. I love Batman/TMNT. Still waiting for The Last Ronin/TDKR.

Thats really cool

Fr ^^. Things can stem from a cheap gimmick and still be good.

^ just look at literally every DC crossover. Batman meeting Superman was a gimmick in the best way possible.

So who teams up with green lantern tails silver knuckles

This is the lineup

Knuckles as superman reminds me of that one big bang theory episode where they go to a costume contest

Not a sonic person so the moment I read Knuckles I thought of this.

It is about time Sonic and Flash had a crossover!

It's about time DC remembered that Barry Allen exists.