General drawbacks for underrated carries

We know the op but underrated stuff, such as Population Bomb Ambipom, but they have drawbacks often (one ferrothorn and your run ends, for example)

So I've cooked up this discussion idea. What are some drawbacks that should be avoided at all costs for the most efficient farming?

Keep in mind this question is wide open for any purpose, whether it is hatching oriented, shiny farming or classic run completion, as well as different modes such as Classic, Endless and Endless Spliced/Fusion