Best grinding location for the last 3 mons i need to grind to e4 cap

I have 3 mons left to grind to lvl 60 for leaf green e4 and blue but i can find a good place to grind them.

the 3 mons are;

1. Jolteon, lvl 53, was grinding in seafoam island and tried on 2 island but both just feel really slow.

2. victreebel, lvl 52, was gonna do it at the same place as jolteon or maybe victory road

3. snorlax, lvl 49, probs just victory road

is there any locations im under estimating for this grind or should i just suck it up and accept the grind will take an age