I would Have to say it is Mudkip. This is because a tough water type is needed a lot in the game. Although Mudkip is good in the beginning of the game I would have to say the best starter is Machop and Charmander because it not only helps in the beginning but it also helps when you have to face Articuno so that is my opinion on the best starter Pokemon.
You Can't
Yes
Yes, he/she can be a starter or your partner.
You can't! You can only get Riolu in Explorers of the Sky.
you have to keep on trying and restarting again and again
get it as your starter or partner. u can also evolve pichu
Wrong answer! They can! You need to go to luminius cave!
Mew isn't available as a starter in Pokemon Mystery Dungeon.
You must have recruted dialga and palkia and finished marine resort
Uhm doood, the hot one? Get her by selecting her!
In Pokémon Mystery Dungeon: Explorers of time\ darkness, a good starter Pokémon is Piplup, however I also find Turtwig Totodile and pikachu good
my advice get lots of reviver seeds and teach ground moves to your starter Pokemon