I have my team already planned except for the last spot. I finally went down to the last 3. Which one out of these do you think I should have?

Alien thing
Venipede final evo
Electric tarantula

(Couldn't remember names)

Galvantula! It's pretty good with thunder.

Well if you don't have a physical attacker yet, then I say go with Scolipede. It can be a little tough to train at first, but once it evolves you will have a powerhouse on your hands. Its quick and hard-hitting, has useful abilities, and with a Heart Scale can learn the powerful Megahorn, as well as TM X-Scissor. It also gets Rock Slide and Earthquake by TM, which are very rare on a Bug type.

I can personally testify that Beheeyem is ah-mazing. He's a great special attacker and gets some good stat boosting moves too. Plus it has the best cry in the 5th gen. But like AM said, if you lack a physical attacker, Scollipede may be the way to go.

Well, since I trained a Galvantula, I'm going to say.... go with Galvantula. Its Compoundeyes + Thunder combo is really useful. Scolipede would also be a good choice *points at Ala's post*.

Hmmmm... seems I chose a good selection, which just makes it harder. I don't bother with EV's IV's stuff like that until I finish the game... so I don't know. My planned team is:
Serperior
Seismitoad
Chandelure
Archeops
Eelektross
[insert pokemon here]

I am not sure how strong Eelektross is. However, if you like it, then I doubt you would need another electric one like Galvantula. I would advise you to choose Scolipede since it is as Kaz said, a very strong Pokémon. You can even find it early in the game, located in Pinwheel Forest.

You find it's first evo in the bottom floor of electric rock cave, with a 5% chance of appearing. Anyway, I guess i'll go with Scolipede then. *sigh* back to Pinwheel Forest!

Would I take it as your question has been answered, or is there anything you want to discuss more?

Just one thing - can anyone suggest a good moveset for Scolipede?

Well, it is week to fire, flying, psychic and rock. I would suggest to have Megahorn, Earthquake, Rock Slide and Poison Jab. Megahorn is a very powerful stab and will also be good against psychic. Earthquake deals with all those who are fire and rock. Rock Slide gets rids of the flying ones, while Poison Jab is yet another stab. If you don't want Poison Jab then you can add one of your choice, but a stab Poison Jab is strong enough.

Since you have an empty slot, may I suggest Haxorus? Its Attack is nearly as high as Rayquaza's and Zekrom's and its Speed is decent. Even though its movepool leaves a bit to be desired, it has EQ to back up your Dragon STAB.