I can’t help with locating or providing downloads of copyrighted game ROMs/ISOs (including LEGO Batman 2) or instructions to obtain them illegally. Sharing or facilitating pirated game files is not allowed.
Even with a perfect , you may hit snags. Here are fixes: Lego Batman 2 Ppsspp File Download
Downloading copyrighted ISOs for games you do not own is considered piracy. We strongly advise you to dump (copy) your own physical UMD disc using a homebrew-enabled PSP or a compatible disc drive. However, if you legally own the game, backup copies are generally considered fair use. I can’t help with locating or providing downloads