Tho I cant disagree with switching espeon out for something like Gardevoir, I'm here to make a case for my fav pokemon Umbreon. (Yes I am biased but pls give me a chance)
I agree completely with not stacking similar types on the same team. I also personally follow this rule. I usually try and pit 6 pokemons with as much type variation as possible as a general rule of thumb. If you want to keep Umbreon and I stress again on IF. You can and should go for cursebreon. I know its a pain in the ass to setup and yes its slow as hell but man I lost count how many times Umbreon saved my ass in Reborn. Its so dang tanky that honestly, type weaknesses don't even matter anymore (once he's set up with Curse). And using the buffs from Curse and Payback just freakin one shots everyone and everything into oblivion regardless of type advantage/disadvantage. You also have wish when you find yourself in 'oh crap you're dying' moments. Just make sure to EV the heck out of your Sp. Deff and have complimenting nature to go with it. Bonus points also given to Umbreon's badass shiny form boy cant go wrong with that.