Hearthpwn

I'll give you a list of the other Pokemon that would be jealous

Bulbasaur, Ivysaur, Venusaur, Bellsprout, Weepinbell, Victreebel, Chikorita, Bayleef, Meganium, Sunkern, Sunflora, Nuzleaf, Shiftry, Tropius, Turtwig, Grotle, Torterra, Wormadam, Snover, Abomasnow, Leafeon, Seawaddle, Swadloon, Leavanny, Cottonee, Flabèbè, Floette, Skiddo, Gogoat, Pumpkaboo, Gourgeist, Rowlet, Dartrix, Decidueye, Fomantis, Lurantis, Bounsweet, Steenee, Tsareena, Kartana

May as well make an easy one

So big, I'd make ivysaur jealous

This is clearly Shieldbearer because, "you shall not pass" am I right?

Absolutely correct it was Angry Chicken

the first two lines refer to the flavour text of Volatile Elemental (which you should definitely look at), if you knew the flavour text you pretty much got the riddle immediately.

The next lines talk about how Angry chicken is such a ridiculous card that if you die to it, you will be laughed at by all who saw. The line "until I get some help" talks about how if Angry Chicken if buffed in health his enrage can trigger

Your turn

This one might be a bit cryptic (or it might be really easy, it's hard to tell)

Volatile , Grommash, Raging Worgen

We met each other through our issues

If by chance, you die to me

Never fear I brought the tissues

When I hit the board, the haters bray

They laugh until to their dismay

I get some help and make them cry,

So embarrassed they want to die

Could it be Elemental Destruction

The first line refers to its mana cost, the second two lines refer to how it's damage varies and the last line is about how it kills minions but it also overloads you a bunch 'depriving' you of your mana

is it Tomb Spider

Is it possibly Wild Pyromancer?

Is it Amani Berserker?

Fight me and I'll probably die, amani does not have lots of health 

spin me up, heat me up, refers to how it is activate dby a whirlwind effect or a mage hero power

throw some berserking in a tea cup, berserker is in the name of this card

then I may be useful, if only in another time, refers to how it can trade with minions much later in the game that have a higher cost than itself

Its Hemet Nesingwary Linklater got it

Ive been on the sidelines too long (Hemet Nesingwary was never played)

Waiting for a chance that never came along (once again, he never saw competitive play)

 Developers made me anew and I didn't mind at all (the new card Hemet, Jungle Hunter gave Hemet a new name)

But still I don't need your help, I fight my own battles (In the tutorial fight with Hemet he introduces hero powers with the line "HEMET FIGHTS HIS OWN BATTLES" and shoots a Stonetusk Boar)

I've been on the sidelines too long

waiting for a chance that never came along

developers made me anew and I didn't mind at all

but still I don't need your help, I fight my own battles

should be pretty easy

What about Prince Malchezaar because they are all the second last legendary of their respective adventure

What about Medivh?

Chromaggus?

Kabal Chemist

Potion card