It was hard to pick a favorite as a who's who of Junior wrestlers kicked off the Asics Junior National Freestyle Championships as one of the toughest fields the tournament has ever seen joined the Cadets in action today at the FargoDome in Fargo, N.D.     Four returning champions,and one Outstanding Wrestler award winner highlighted the parade of wrestling stars.     Everybody's eyes were on Steven Mocco (275) of New Jersey and Nick Simmons (123) of Michigan, two of the most dominant wrestlers the Junior level has ever seen. Simmons is looking to etch his name in the history books with a fourth straight win, while Mocco is vying for his third consecutive title without allowing a single point.      Neither of them disappointed as Mocco won his only bout of the day by a 10-0 technical fall in just over one minute while Simmons won his two matches by a 10-0 technical fall and a 45 second pin.    This year's Greco-Roman champion and Outstanding Wrestler Sam Hazewinkel (114.5) of Florida started his quest for a double championship leaving no doubts about his chances of winning. He didn't allow a point in beating both of his opponents by technical fall scores of 10-0 and 12-0.    Hazewinkel will more than likely have to contend with returning champion Nathan Kendjorsky (114.5) of Ohio if he wants to take home his second championship. Kendjorsky didn't allow his opponents any breathing room by winning by a pin in 1:27 and an 11-0 technical fall.     Other Greco-Roman champions in search of a double victory are Gabriel Mooney (98) of Minnesota and Brock Zollinger (105.5) of Idaho. Mooney won his only bout of the day 10-0, while Zollinger scored a 14-3 technical fall victory.     The Juniors weren't the only wrestlers in action as the Cadets took the mats for their second day of competition.    Cadet Greco-Roman National Champion Patrick Barrentine (242) of Ohio finally met his match today as Jon May (242) of Minnesota handed him his first loss. May defeated Barrentine 11-10 to improve his tournament record to 6-0. Three of his wins have come by technical fall, while he won another by pin.     Barrentine was a monster on the day in the rest of his matches, winning with a 51 second pin, an 11-0 technical fall and a 10-1 decision to move his record to 5-1 in freestyle.     Grant Miller (209) of Illinois continued his brilliance on the mat with four wins - three of them by technical fall shutouts and one with a pin in one minute and seven seconds. Miller is rolling through his competition as he has not allowed a point all week en route to the Greco-Roman championship nor through the preliminary rounds of the freestyle championships.     This year's Greco-Roman Outstanding Wrestler Eric Tannenbaum (132) of Illinois breezed through three of his matches today with three 11-0 technical fall victories, but met a tough challenge against Utah's Cam Dansie (132). In a tight match, Tannenbaum pulled out the 5-4 victory to improve his freestyle record to 8-0. Dansie lost his second match of the day to Matt Coughlin (132) of Indiana who pinned Dansie in 3:51 to move to 8-0.    Returning champions Charlie Falck (103.5) of Minnesota had no trouble today, winning all four of his matches to improve to 6-0.     Wrestling continues Friday with the Cadet championships and medal matches while the Juniors will compete in the second day of preliminaries.