How come specific champs have unique summoner spells that help evade other summoner spells, but not 
's W I love playing as but it bothers me that her W cant juke or doge most spells like 
's ult or 
's ult. I just believe if you can jump over a large wall with that you should as well be able to jump over spells, as well as 
's E or 
's ult. I would just like it if they could make a patch to where i can evade and initiate and make the game more interesting.
She can jump J4 ult. Technically she can dodge other spells, just not jump over them which is actually a healthy mechanic because having a high burst high mobility long ranged hyper carry adc who can get about 1.5 seconds of invulnerability would be silly.
I have no idea what you're trying to say here. Summoner spells are these 
{{summoner:2}} 
etc. Are you talking about champion abilities? That's what Trist's W is, and it can be used to get out of J4's ult and evade things like Jinx and Ez ults. The reason it can't be used to get out of Veigar's E is because Veigar's E specifically stops dashes, and Trist's W is a dash.
If I'm right, you want Trist's W to be a blink like Ezreal's E or Flash. If that's correct, I think that's a horrible idea considering that Trist is already one of the safest Marksmen in the game.
How come specific champs have unique summoner spells that help evade other summoner spells...
As a heads up, you mean "Champion Abilities." "Summoner Spells" exist, and are things like Flash, Heal, Teleport, etc.
Further, there are actually NO abilities that aren't blinks (like Ezreal's E) or invulnerability states (like Fizz's pole or Elise's Spiderform E) that can bypass this sort of thing: this is because League of Legends doesn't have a Z axis coded for movement, so any non-instant movement is coded as a dash. Some dashes like Tristana's can go over terrain, but no dashes bypass obstacles. Tristana's is just odd visually since it's one of the "highest" jumps among dashes.
Allowing her to bypass spells in this manner would be a HUGE power boost to her though, and would require cutting a lot of her actual carry potential. I don't feel that's worth the trade.
Jinx and Ezreal's ult is kinda good but Veigar's W and J4's ult would be broken and unhealthy to the game.
