Semi-Pseudo is a term used to describe a Pokémon who is often mistaken for a pseudo-Legendary, but fail to meet the criteria to be a pseudo-legendary. The most notable example of this lies in the fact that all the semi-pseudos have a base stat total that does not equal 600, so they cannot be considered pseudo-legendary by definition. Pseudo-legendary Pokémon are usually uncommon/rare.
Hoenn is the only region, as of yet, to contain 2 pseudo-Legendary Pokémon.
Coincidentally, they are usually found in hard-to-find places. For example: Bagon (Salamence's basic stage) can only be found at the back of Meteor Falls Cave with the use of Surf and Waterfall, meaning that you'd need eight Gym Badges to even think about going there and Metagross can only be obtained after the player defeats the Elite Four and Steven, the player must then go to Steven's house, the player then receives a Beldum.
Flygon, a semi-pseudo-legendary, is also found in Hoenn.
Lucario and Zoroark are mistaken as Pseudo-Legendaries because of the way in which they are to be obtained.
Zoroark was once only able to be caught as an event. Because of this, it is mistaken as a Legendary. Zoroark could be obtained when either the event Raikou, Entei or Suicune was taken to Lostlorn Forest outside Nimbasa City in the first Black & White. It was also possible to obtain Zoroark's pre-evolution, Zorua, but Zorua needed an event Celebi to be captured in Black & White. However in Black & White 2 the player is given a Zorua by the sage in Driftveil City provided they have room in their party for it to fit, it seems that it was once belonged to N. In Generation VI player characters in the Pokémon Village or on Route 20 have a low chance of running into a wild Zoroark.
Tyranitar and Metagross are the only pseudos that cannot learn Dragon-type moves by leveling up.
However, Metagross is the only Pseudo-Legendary that cannot learn a Dragon-type move at all.
All pseudo-legendary have been used in a battle with a champion at one time or another: Lance has a Dragonite in Gold/Silver. Gary (Blue/Green) has a Tyranitar in the rematch in FireRed/LeafGreen. Steven has a Metagross. Lance has a Salamance in the Pokémon Black and White 2 world tournament. Cynthia has a Garchomp. Iris had a Hydreigon and Diantha has a Goodra.
All pseudo-legendary, at level 100 has the total experience of 1,250,000.
Goodra is the only Psuedo-Legendary with one type.
Most Pseudo-legendaries have a 4x weakness except Goodra and Metagross.
Out of the seven Pseudo's, four of them can mega-evolve, while two out of the nine Semi-Pseudo's can.