Abra I think is easier to evolve than Budew, just because it evolves at a guaranteed lvl, so all you need to do is train it, using whatever method you use [hidden power, exp. share, switching, etc]
Budew evolves through taming [happiness], which makes it a LOT more difficult to evolve, as for most people, it doesn't evolve until the high 20's~30s.
You need at LEAST two hearts [takes a while to get there], though I think you need a bit more happiness than the minimum to get the 2 hearts, and you have to lvl it during the day time, when it's bright and sunny :3
To train, I'd probably have to say Abra, though, as it only knows two moves, only one able to cause damage, and you have no idea as the the power of the move, while Budew at least gets STAB Mega Drain/Absorb with stun spore.
To evolve it, budew takes the prize for being harder to evolve between those two :3
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