this shouldn't count anymore since ben's been upgraded.however,if kid ben is being used,then I'm not sure.speed equalized does make this fairer,but I can't see what spidey's webs could do to ben that most of his go to forms couldn't escape.this would lead to spiderman having to resort to close combat,which would lead to ben having the advantage depending on his form.this really depends on what ben chooses.although idk much abt spidey,the timer makes it so ben has to pick the right form from the beginning and beat spiderman within 5-15 mins unless he gets lucky with an instant recharge.ben is most likely to go fourarms,diamondhead,heatblast,xlr8 or cannonbolt,and maybe upchcuck,seeing as this is 10 year old ben.heatblast is only MCB level,but he can burn through spidey's webs.and if he turns up his heat,spiderman might have trouble touching him,but the only way heatblast can win is if he gets extremely mad and cuts loose,which i don't see happening at all unless spiderman somehow manages to get gwen killed or something,which also obviously won't happen.xlr8 could honestly win,as although he is MCB level,he could cut through the webs,and use a tornado to cut off spidey's oxygen supply (making tornadoes is in character for him).diamondhead is small town level,and can very easily cut through the webs as well,forcing spidey into close quarters,and diamondhead has an immense versatilty advantage with his crystal manipulation,and can encase spiderman in diamonds,which is definitely an insta win(and in character too).fourarms might be able to rip through the webs,and forcie spiderman into close quarters again,which will lead to ben having the advantage,with his two extra arms,and he can also use his 'big smack' if spiderman tries to dodge around.upchuck would probably lose,but he can eat the webs shot at him,again,forcing spiderman into close quarters,and swallow him and spit him back out once he gets close(although only teen ben has used this tactic,so most likely a loss for upchuck) cannonbolt could potentially win thanks to speed being equalized.if he uses that pinball tactic he used against kevin,he can most likely beat spiderman,however,if he gets tangled up in webs,then its game over.other aliens I can see beating spiderman are maybe ghostfreak(which is out of character for kid ben anyway) and definitely way big,but thanks to the limiter on the watch,if ben is getting overwhelmed he will most likely lose before he can go way big,which isn't really his go to anyway.so I'd say kid ben wins with high difficulty,because out of most of his go to forms,I see most of them winning against spiderman.
that being said,this is only if we're assuming that the watch doesn't mess up and turn ben into grey matter or something.