The search term consists of three distinct components:
You will find dozens of Russian and Eastern European forums discussing a "ported" Castle Crashers for the PSP. These threads usually contain a file named CRASHERS_PSP_171.iso . Here is the reality of that file: castle crashers psp iso 171
Get the PS Vita version (if you own a Vita) or the Switch version (best modern portable option). The search term consists of three distinct components: