The scrambled sprites are most likely caused by Missingno., but they can be fixed easily. Just look at the Pokedex entry for a legit Pokemon and it'll fix itself. However, the HP bar and Glitch City like effects are kind of unexplainable. Glitch City and Missingno. are both almost harmless, so they are probably the results of a different glitch (like the expanding HP bar which is common in many glitches like the ZZAZZ trainer glitch).