Jango made an appearance in Rockman EXE 4, and Rockman makes an appearance in Boktai 2. But you can link-up Rockman EXE 5 and Boktai 2 for a special wireless-only Crossover Battle. The two games have totally different systems, so you can't battle directly, rather you each have to fight a special boss, Shademan, on your own game and the first person to beat it wins. Apparently doing this will allow you to get some special chips in Rockman EXE.
This was revealed in a two-way interview with Kojima and Inafune in the new Famitsu.
This was revealed in a two-way interview with Kojima and Inafune in the new Famitsu.