Just a little tip that might work (especially for casual/beginner players):
1. Choose a starter.
In every Pokemon game, the starter is either partially or fully grass, water, and fire types. I would recommend NOT to choose a grass type if you are new to Pokemon game. The reason for this is that grass has too many weaknesses (weak from poison, ice, fire, flying, and bug). This is troublesome for a beginner player. You need a somewhat strong starter to get through low levels. You can choose to either ditch the starter later on or keep it. Grass pokemon can be strong if built right, but the learning curve for grass is higher compared to water and fire.
2. Make your own Pokemon squad.
If you are new to the Pokemon game, choose a strong team. Please, don't choose a Pokemon cause they are cute, small, fierce-looking, or whatever. Just don't look at their appearances to based on. Instead, look up at their base stats here:
http://www.serebii.net/pokedex-bw/I would say if one of the base stats are slightly over 100, that Pokemon is mediocre or even crappy. Depends on how other stats are. If one of the stats are over 130, that means the Pokemon is excellent at that particular stat. You should boost that stat up by EV (Effort Value) training.
More info on EV training:
http://www.serebii.net/games/evs.shtmlThe Pokemon cannot be IV (Individual Value) training, but it can be bred over and over to get the IV that you want. This isn't easy since it requires patience and chain breeding and some luck of course.
More info on IV:
http://www.serebii.net/games/ivs.shtmlPokemon's Nature is also important. Nature can either boost one stat and lowering another stat or it doesn't boost and lower any stats (neutral nature). Let me tell you this, the neutral natures are crap and you shouldn't go with this. Pick a nature that boosts the stat that you need and lowering the one that you don't need. Example: Garchomp excels at physical attack. Pick a nature that boosts his physical attack and lower the special attack. You won't lose anything by having a lower special attack stat since you're not putting any special attack skills on him.
More info on Natures:
http://www.serebii.net/games/natures.shtml3. Skillset
Each Pokemon is either a dual-type or just a single-type. Dual-type can be an advantage or disadvantage, depends on the combination of the types. Sometimes, dual-type makes your Pokemon having more weaknesses than if it's just a single-type or it can be the other way around. Dual-type gives less weaknesses than if it's just a single-type.
More info on Pokemon's types and weaknesses:
http://www.serebii.net/games/type.shtmlAlso, a Pokemon deals more damage for the skill that has the same type as the Pokemon. For example: Garchomp vs Electivire. Garchomp is a dragon/ground type, while Electivire is an electric type. Both Pokemons can learn Earthquake. By default, Garchomp base earthquake damage will be higher than Electivire because Garchomp is a partially ground type. I don't remember how much more damage it does (I believe it's 1.2x base). So, Garchomp's earthquake has a base of 1.2 x 100 = 120 base earthquake, while Electivire's base earthquake is just multiplied by 1, so it's just 100 base earthquake. Best to have one skill that is the same type as the Pokemon for the base damage boost.
Other skillsets:
1) Learn skills on your Pokemon that you can use to counter your weaknesses. For example: Garchomp is a dragon/ground type. It's weak to ice attack (very weak, 4x super effective) and dragon attack (weak, 2x super effective). Make a skillset that you can use to counter your enemies. My Garchomp has:
-Earthquake (damage boost from a partial ground type)
-Dragon Claw (damage boost from a partial dragon type, as well as to counter dragon pokemons)
-Fire Fang (to counter ice pokemon)
-Stone Edge (to counter ice pokemon, as well as to hit flying pokemon that's immune from earthquake)
2) Learn skills to counter immunities. The Stone Edge example on Garchomp is a good way to counter flying pokemons that is immune from any ground attack. With a rock-type move, you can hit super-effective on those flying pokemons. Another example: Gengar is a ghost/poison pokemon. Obviously, any Ghost-based skill wouldn't do any damage to a normal pokemon. Put a fighting-type skill to hit super-effective on those normal pokemons. I put Focus Blast on my Gengar since mine is an sp attacker, Focus Blast is an sp-based attack.
**Lastly, get various types of Pokemons possible! and Happy battling!** :O