lol al bhed

Anyway I'll do them in hebrew (using english letters, and using the same list of names you used:

The Pokemasters - Alufei-HaPokemonim

Pokemaster Kevin - Aluf-Pokemon Kevin
Little_Pikachu - Pikachu_K'tana
Lady Vulpix - Giveret Vulpiks
Austrian ViceMaster Alex - Shalit-Sheni Ostri Aleks
RedStarWarrior - LochemKochavAdom
mr_pikachu - mar_pikachu
Number1ChanseyFan - OhedChanseyMispar1
Roarkiller - Rotzeach-Sho'eg
Last Exile - Galut Sofit
Dark-San - Choshech-san
The_Missing_Link - HaChuliya_HaChasera
Hypotenuse Man - Eesh Yeter
River - Nahar
Mistysakura - Mistisakura (reading them both as names)
darktyranitar - TairanitarKeheh
Saffire Persian - Sapir_Parasi
Weasel Overlord - Samur Adon-Elion
Wolfsong - Shir-Ze'ev
Blademaster - Adon-Lahav
Heald - Hild (isn't that a name?)
Inferno_Dragon - Drakon_Gehinom
Master of Paradox - Shalit Paradoks
Mystic_Clown - Leitzan_Mistikai
Knight of Time - Abir Z'man
Crazy Elf Boy - Yeled Gamad Meshuga
firepokemon - Pokemon Esh
ACE135CC - ASS135CC (No joke, that is how you say the card)
shinypkmnchaser - rodefpokemonnotzetz
CuteLassJigglypuff - YaldaChamudaJiglipaf
Crystal Mew - Myu B'dolach
Toxicity - Re'ilut
Starry Might - Ko'ach Kochavim
Charles Legend - Charels Agada
AntiAsh Superstar Anti-Ash-Kochav-Al
Mega Horny - Mega-Merugash
Dark Sage - Chacham Koder
Phoenixsong - Shir-Of-Chol
Perfect Chaos - Tohu-Bohu Mushlam
Crystalmaster Mike - Adon-B'dolach Maik
Houndoom_Lover - Ohev_Howndum