It would be possible to use the Slakoth, but it would require a lot more seeds that I'd be willing to part with. Also I'm quite averse to EXP down over a lot of other seemingly "neutral" downsides. It's actually quite hard on your resources, being ALMOST as bad as training up a Pseudo (20% vs 32%).
Also apparently Psyduck/Golduck can pick up 4 Apples at level 30, making it quite good at filling in ingredient gaps, on top of its incredible skill trigger rate.
>>55589456Given how uncommon Mareep candies are to come by, I'd advise against that. Having Inventory Up at 25 is a big nothing, and you're currently only looking forward to Helping Speed M at 50. It's also a pokemon that you really want to dump Main Skill candies into, which is a very steep investment to make.