Get any digital reverb delay pedal which features reverse delay, for the backwards guitar sounds heard on some tracks such as ‘Rain’.
Even a cheap Casio will sound like something out of a Beatles record! The great thing about this pedal is that you can eighter plug your guitar to it and create what sounds like a background Mellotron accompaniment, when you blend effects and dry sounds, OR, you can plug a keyboard to the pedal and play wet-signal only, as if it as a real Mellotron. More interestingly, you can also get a few FX pedals to achieve some sounds from the Fab Four psychedelic era – reproducing the sounds of other instruments and studio effects used by the Beatles in the studio:
Other than that, George used some Wah in the later days of the Beatles, so the Vox Wah or Dunlop Cry Baby will be just perfect. The Way Huge Havalina fuzz is a well-priced modern option – a germanium fuzz that does the Tone Bender sound really well!