Basically, Electrode is just a bigger version of Voltorb, but the top and bottom colors have been switched for some reason. It seems pretty arbitrary, and is definitely odd, but not necessarily odd enough to get itself on this list. What's real weird is that it gains a mouth too. Where there was no mouth before (essentially just a Pokemon with eyes), it now has a mouth and teeth and everything. The existence of a mouth at all indicates it needs to eat and breath. How that was happening when it was a mouthless Voltorb is a mystery for only the bravest Pokemon fanfic writers.
Geodude and Graveler follow a pretty normal evolutionary pattern: it starts out as a little rock creature, it grows into a bigger rock creature. But something weird happens when Graveler evolves into Golem it turns from a creature made entirely out of rock to a what looks like a lizard-like thing trapped inside a boulder. The point is, it goes from all rock to some kind of organic creature living inside a rock, like when Dwayne Johnson emerged from The Rock.
With evolution comes the use of more complex tools this is evident in the fossil records of humanity's own history. However, "holding two spoons instead of one spoon" is a little different twist on that concept. In the transition from Kadabra to Alakazam, the Pokemon grows a bit, but the primary difference is that it is now holding one additional spoon. Likewise, the "urr" line of Pokemon from Black/White (Timburr, Gurdurr, and Conkeldurr) get bigger and stronger, but tow different types of beams along with them (wood to steel to rock, respectively). Why each species has a specific type of beam is a little strange surely Conkeldurr (side note: these Pokemon have some of the most insulting-feeling names) would do better with a steel beam than a couple of rock ones, right? Nope he's evolved now, so he has to use rocks.
It could be worse, though. Poor Farfetch'd holds a leek normally, but in his evolved form he OH WAIT, Farfetch'd doesn't HAVE an evolved form. It's stuck holding an onion as its only weapon for the rest of eternity. Someone get that Pokemon some Burn Heal.