Playing this type of game is a simulator 'coz you can change everything - from their hold items, abilities, moves, and natures. Changing them drastically in worst way may messed up your entire game (Remember it's a live battle even you're just a guest.)
 
                        Registering is just in your fingertips, what you need is only a unique nickname and a password. Battling as a guest is good but in case you won consecutive battles... I recommend you to register so you can record your rank. There are also a lot of avatars you can choose. Most of the male players choose Ash. You can also change the scene of the page in different wallpapers. How exciting right?

                        This what makes the game a little bit difficult. If you are a player who have a pokemon goes through you mind to choose, let me help you. Always remember that the easiest way to rank up is to control the entire battle. (I'm not going to tell you who yo use.)
                        Here where you should start is by picking those 'mons to your party. First is to choose what type of battle you're about to join. (Not all of the pokemon are usable.) Game battles don't allowed using some ability of the party. the most challenging battle is the OU, 90% of the players used legendaries with differnet type of status (IV's and I's) and also the nature. In choosing pokemon, use different types and weaknesses 'coz having the same may put you in the bottom.

                         I know you don't want Blaziken to use water gun or Gyarados with a vine whip. Make sure to use their appropriate moves ( You can have them in your Pokedex and game boy) give them usable items that suits them. If you are joining a doubles ( Battle) I recommend weather type in your party as the manipulator. their weather moves makes certain pokemons weakens or strenghten. In a triple match, use different types to stand a chance of winning. Ghost and Dragon type weaknesses are their selves, for you to win, Remember to use the most effective move specially SPATK. Now start your team and Break a leg!!!  Visit this link for the game site  http://pokemonshowdown.com/