Razz Poker 
Razz is a 7 card stud game for low only.  In this game, there is no qualifier for low (like in Stud 8 or Omaha 8, your low hand must be 8 or under).  In Razz, the winning hand is simply the 5 lowest ranked cards (worst hand). Straights and flushes do not counts against you.  Aces are low, so the best possible hand is a wheel (A-2-3-4-5). See Stud rules for dealing of cards.  In Razz the highest door card opens the betting or brings-in.  Action continues from the lowest hand showing leftward on following rounds. For example:  HAND A - Ks 7c 1c 2c 5c 6c 5s is a strong hand and would be called a 7-low, meaning there are 5 cards ranked 7 and under (the flush does not matter).  HAND B – Jc Qs 7d 1d 3h 5h 6h is also a 7-low but loses to Hand A because the 3 is higher than the 2. Another example:  HAND C – 5s 5d 10d 9d Qs Qc Qs (a 5’s paired low hand) is lowerthan HAND D – As 2c 9s 9c 9h 8c 8s (an 8’s paired low hand), and HAND E – 9 Q J 10 2 A A (a 10-low hand) is lower than HAND F – A 2 3 4 K J Q (a K-low hand).
7-Card Stud Hi-Lo (eight or better) 
The general rules of Stud apply in Stud Hi-Lo, except that (A) 2 hands split the pot: the highest and the lowest, and (B) there is no option for a double bet if the door card is paired by the next up card. Like Omaha hi-lo a low hand cannot have any card higher than an 8 and straights or flushes do not matter for low hand. [See Omaha hi-lo rules for example of low hand]
Omaha Hi/Lo Rules 
Just like in Omaha Poker, the rules are that each player gets 4 pocket cards face down and 5 community cards dealt face up (flopped in the same manner as Texas Holdem). The winning hand must have 2 pocket cards, and 3 community cards. In Omaha Hi-Lo two hands split the pot: the highest and the lowest. A low hand cannot have any card higher than an 8 and in Omaha Hi-Lo straights or flushes do not matter in a low hand, however, if your low card pairs a card on the board it is counterfeited.  Aces, by the way, are both a high and low card, and you can use the same hold card for both your high and low hands. For example, your hand is:  As 2d 4s Kh (a very good starting hand)…board flops: 5d 2c 4d…you do not yet have a low hand as you need 3 low cards on board AND 2 different low cards in your hand…now if the board turns a 3h, you have the nuts both high and low (A 2 3 4 5 is the best low there is; called a “wheel”) and you also have a 6-high straight for your high hand…the river comes Kd and you likely lost the high part of your hand to a flush.  NOTE - A, 2, 3, 4 and 5 of no flush often wins both high and low.  You can also have a wheel with an Ace-high flush by the river, and win both high and low hands.
Omaha Rules 
The difference between Omaha poker rules and traditional Texas Hold‘em is instead of 2 pocket cards face down, each player starts with 4, and at showdown, players must use only 2 of their 4 cards in combination with only 3 of the community cards to create the best 5-card hand.
7-Card Stud Rules 
There is no “button” in stud games.  Cards are dealt left to right, seat 1 to seat 10.  Each player is initially dealt 2 cards face down, called “hole” cards and 1 card face up, called the “door” card. The player showing the lowest door card (if same rank, then lowest suit of that rank – 2 of clubs is the lowest card in the deck) is required to post the initial bet or “bring-in” (the bring-in is like a blind where it is a required minimal bet).  They have an option to post the bring-in or a full bet.  Play then goes around the table left of the opening player.  Action on following betting rounds starts with the highest hand facing up.  Each remaining player will be dealt one additional up card until there are 4 cards facing up, then the last card is dealt face down.  Betting rounds occur on the door card and each additional up card and the final down card. NOTE:  If a player’s door card is paired by the next up card, they have the option of doubling the round’s regular bet size.  New pairs are always announced by the ​dealer on all rounds. Showdown after 7 cards to each player in the hand.  You play the five best cards of seven.  Regular poker hand ranks apply to the best 5 of your seven cards.