Why not? They are similar in many ways.  Both are blue, mad scientists as villains, animal friends, friendly rivals (Protoman, Knuckles), dark rivals (Bass, Shadow) collecting things (Beat parts, Chaos Emeralds) friends who are mechanicly inclined (Dr.Light, Tails).  Does anyone else agree?

You know was thinking about that but it was MegaMan Starforce and Next-Gen Sonic,but classics is probably better saying that.This is how they connected.

MegaMan&Sonic=both blue,have special skills,have a fancy nickname with the word blue in it,and are the main protaganist as the title is named after them.

ProtoMan&Knuckles=both red,was originally was the main hero's enemy,are now their sidekick,help the main character,but argues with them,share a bromance,were used by the main villian,and are friendly rivals to main characters.

Bass&Shadow=both are black,used to be evil,have a dark agenda,think they are the ultimate being,they use to work for the main villian,but now fight against them,are probably stronger than the main character and share some of their abilities, and is the main character's dark rival but will be their ally if neccessary.

Roll&Amy=both share a romantic connection to the main character,care about the main character deeply,wear a dress,have a odd weapon,and wear some kind of head gear.

Auto&Tails=both are engineers,make new weapons and new gadgets for the main character,are useless in battle,but makes good gear and is the brains of the team,and are both intellectual and witty,but a bit childish.

Dr.Wily&Dr.Eggman=both are mad scientist,evil genius,plans to take over the world,mentioned in all the games as the main villian,the main antigonist,are bald,have big mustaches,make machines for the main character to face,but loses anyway,will always come back wanting revenge no matter how many times they get beating by the main character,and a lot of their allies eventually betray them.

I think Sega ripped off of Capcom cuz MegaMan came before Sonic,but if that's the case then Sega's next move should be a Sonic MegaMan crossover game I mean they did it with Mario twice and MegaMan have alot in common with MegaMan.

I fail to see what is so funny, it is a great idea, the blue bomber with the blue dude with the tude stopping a combined effort of Wily and Eggman, for they have merged the egg fortress with wilys skull fortress and plan to take over both worlds while Sonic and MegaMan head out to collect the chaos emeralds and duos hyper bolts to create weaponry that would allow megaman and sonic to perform team attacks such as the sonic buster.

Its a terrible Idea. It reeks of milking, and fanfiction. They live in completely different universes, and in different timelines. The most we would see in the megaman universe would be Shadow and Omega, since they don't age.

Hmm....... I thought they already tried a crossover at one point. X_X