Raptor, when using DSPECIAL with over 100% Stand Meter, can negate opponents' effects. The implementation is simple, so here's how to do it:

In init, define the variable raptor_has_custom_null. You can set it to whatever you want, but Raptor checks if the variable is defined in the character. This tells Raptor during his checks that your character has a custom dispel. So, for example:
// this character has g. raptor compatibility (this character is cool)
raptor_has_custom_null = 1;

When Raptor sends out his dispel, he sets the variable ucr_meter_null to 1 for one frame. Because of this, put this code into update.gml:
// g. raptor compatibility (this character is cool)
with (oPlayer) if (url == 2906702804) {
if (ucr_meter_null == 1) {
// change your variable(s) here
}}
Note that usually, Raptor tries to make it look like the character that is getting dispelled is doing the reductions, so this would be setting articles to do what they would normally do if the base character destroyed them, or certain effects for meter reduction (i.e. Spamton has a set of lines to play when he has his Kromer reduced).

First of all, if you've put in a custom compatibility, put it here! You don't have to, but it'd be cool.
Second, a full list of every compatibility is located mainly within Raptor's user_event0.gml. There will be a spreadsheet of every built-in compat coming soon™, but it should be finished soon.


With all this out of the way, have fun!