One that most people will have heard of, the mono-type challenge involves the player only using Pokemon of one particular type. Usually, the rules allow the use of dual-type Pokemon, as well as the use of any Pokemon that are not that type to begin with but will eventually evolve into that type (note that this does not apply the other way around - you cannot use Bellossom
on a Poison challenge, for example). Otherwise, you play as normal. HM Slaves (Pokemon caught solely for the purpose of HMs such as Cut and Rock Smash) ARE allowed, but shouldn't be used in battle wherever possible. Any of the seventeen types are possible, but obviously some will be much, much harder to complete the challenge with than others. You must obtain a Pokemon of your chosen type as soon as possible, however. For example, say you choose the
Flying-type, then as soon as you get some Poke Balls, catch a Pidgey
and drop your starter in the PC. Of course, that's the ideal way - it's your challenge, so you are welcome to bend the rules a little if you're insecure about your Pokemon surviving.
The hardest types to do would probably be Dragon and Ghost. Dragon would only give you Horsea
to use, while Ghost allows just Misdreavus
. All the other types have more to use prior to the Elite Four although many types aren't especially early.
For the best experience you will probably want to choose a type where you can get something of that type early on. Before finishing the first gym, you can already start a mono challenge for most of the types, and even have more than one Pokemon for a couple of them like Normal, Flying or Ground.
These challenges aren't always that hard unless you happen to have a type that is a bit on the bad side (ie Bug, not counting Scyther
) but they can be pretty fun, especally for a type like Water where you have a hell of a lot of choices.