Alrighty then! *cracks knuckles* Let's see what we have here!
Let's start with the typings we know you'll have and go from there. Here's each of your Pokemon's weaknesses (crossed out means that there's already a Pokemon on your team who has a type that can trump it):
- Umbreon - Bug / Fighting
- Arcanine - Rock / Ground / Water
- Poliwrath - Flying / Psychic / Electric / Grass
- Luxray/Raichu/Ampharos - Ground
Okay, so based off of that you have two weaknesses (Fighting/Electric) that you can't properly counter. For Electric there's only ground types and for Fighting there's Psychic and Flying. Let's say you put either Machamp or Lucario in your team, here's what it'll look like:
- Lucario - Fighting / Fire
So that would be two Pokemon that have a weakness that can't be countered (Fighting types), so a flying or a psychic Pokemon would be a must.
- Machamp - Flying / Psychic
With Machamp, you're back to choosing Pokemon with Gound, Psychic, or Flying types.
Based off of these choices, here's Pokemon that you can choose from that can counter both types:
- Claydol (Ground/Psychic) Water / Grass / Dark / Ghost / Bug / Ice
- Gliscor (Ground/Flying) Ice / Water
Or... if you don't want those Pokemon, you can always choose a type that's just Ground, Flying, or Psychic (Flying or Psychic is a must if you choose Lucario). It wont be the end of your team if you dont have a Proper Pokemon that can counter an Electric type (you can always switch in one of your own Electric types to stall it.). If you chose another Dark type (with Lucario), that would be three Pokemon who would be weak against Fighting... and I gotta say that having 3 of your Pokemon out of the picture isn't a pretty scenerio. If you really wanted another Dark type though, Spiritomb would be a great add (he has no weaknesses, and is immune to Psychic and Fighting attacks).
As for choosing between the Electric types, it's all about what you want. Do you want an Attacker (Luxray), Special Attacker (Ampharos), or a mixed attacker (Raichu)? Or you might even look into having a Jolteon, because your team could use some speed, regardless of the three Pokemon I recommended to you (Your team isn't the fastest one out there... even with Arcanine). I'll give you the highlights of each Electric Pokemon:
- Ampharos (Great Special Attack, Solid Special Defense, and good HP as well... but its Speed is definitely lacking)
- HP: 90
- Atk: 75
- Def: 75
- SpA: 115
- SpD: 90
- Spe: 55
- Luxray (Great Attack, solid Special Attack as well, HP and Defenses aren't horrible either. But the Speed wont give you many first attacks)
- HP: 80
- Atk: 120
- Def: 79
- SpA: 95
- SpD: 79
- Spe: 70
- Raichu (It's got solid Attack and Special Attack, and it's Speed makes it shine... but that HP and Defense make it a glass cannon.)
- HP: 60
- Atk: 90
- Def: 50
- SpA: 90
- SpD: 80
- Spe: 100
- Jolteon (While Defensively it's pretty bad, it's awesome speed and Special Attack make it a quick and powerful attaker. There's not too many Pokemon who can outrun Jolteon)
- HP: 65
- Atk: 65
- Def: 60
- SpA: 110
- SpD: 95
- Spe: 130
Here's my recommendation for your team (In the end it's all about what you want anyway, so don't feel pressured into only choosing from this set. It's a team that I think will be the most effective against other "balanced" teams):
1. Arcanine: Mixed Attacker
2. Umbreon: Defensive Attacker
3. Poliwrath: Sleep Inducer/Focus Pawncher
4a. Jolteon: Special Speedster
4b. Luxray: Mixed Attacker
5. Machamp: Physical Attacker
6a. Gliscor: Defensive Attacker
6b. Claydol: Defensive Staller
