for the first question is because maylene is powerful in the anime and I think because of huge power. dont say psychic type moves are special because it is never proven special and physical attack exist in the anime.
and for the second question is because lugia is a support Pokemon to eject the meditites.
the third question is pick 4 Pokemon (mostly super effective) and battle another Pokemon and beat it with combos. the fourth part is all Pokemon have 1 typing. no dual types which means yveltal for say isnt weak to rock anymore. the typing that is selected is the primary type and yveltals primary type is dark secondary being flying. some Pokemon appears shiny and have the other typing but they are completely diffrent Pokemons. I'm sorry if this is confusing but this is the best way I can put it.